Information processing apparatus, tape device, and computer-readable medium storing program

ABSTRACT

An acquisition unit of an information processing apparatus acquires access information indicating the state of access to a volume of a disk device at least for data read. A determination unit detects a volume in which a sequential read was performed, on the basis of the acquired access information, and determines the volume as a backup source for a backup.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefits of priority ofthe prior Japanese Patent Application No. 2010-225517, filed on Oct. 5,2010, the entire contents of which are incorporated herein by reference.

FIELD

The embodiments discussed herein relate to an information processingapparatus, tape device, and computer-readable recording medium storing aprogram, for managing a storage device.

BACKGROUND

In computer systems, a large amount of data is stored in a storagedevice such as a disk device or a tape device. Most of the data in thestorage device is periodically backed up to another storage device incase of data loss.

In an existing backup system, data is backed up in accordance with aninstruction from a backup server, for example. A system administratorschedules backup jobs with his/her experience, and sets the schedule inthe backup server. In accordance with the schedule, the backup serveraccesses a storage device and performs data backup.

In many cases, backup is performed during night because there are a fewaccesses to a disk device. During the backup, some backup jobs may beexecuted simultaneously. To this end, resources may be appropriatelyallocated to the backup jobs. For example, there is a technique ofreserving resources for backup tasks on the basis of estimatedutilization of the resources. Please refer to Japanese Laid-open PatentPublication No. 2008-251001.

By the way, a storage device such as a disk device or tape device iscapable of acquiring internal access information such as accessfrequency. By comparing the acquired access information with a backupsource volume, efficiency of the entire process of the system may beimproved. For example, the processing efficiency of the system as awhole may be improved by performing backup while data in a backup sourcestorage device has low access frequency.

However, a function of collecting access information within a storagedevice and an application software product for management of a storagedevice do not acquire the execution state of backup, which preventseffective use of the access information acquired by the storage devicefor improving processing efficiency.

SUMMARY

According to one embodiment, an information processing apparatusincludes: an acquisition unit that acquires access informationindicating a state of access to a volume of a disk device at least fordata read; and a determination unit that detects a volume in which asequential read was performed, on the basis of the acquired accessinformation, and determines the detected volume as a backup sourcevolume for a backup.

The object and advantages of the invention will be realized and attainedby means of the elements and combinations particularly pointed out inthe claims.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and arenot restrictive of the invention, as claimed.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 illustrates a configuration of a first embodiment;

FIG. 2 illustrates an example hardware configuration of an informationprocessing apparatus employed in the first embodiment;

FIG. 3 illustrates an example system configuration according to a secondembodiment;

FIG. 4 illustrates an example backup schedule to be improved;

FIG. 5 illustrates an example backup in which delay control for delayingan operation of a tape drive is effective;

FIG. 6 is a functional block diagram of a disk device;

FIG. 7 illustrates example tables stored in a management table storageunit of the disk device;

FIG. 8 is a functional block diagram of a tape device;

FIG. 9 illustrates an example internal configuration of a drive module;

FIG. 10 illustrates example tables stored in a management table storageunit in the tape device;

FIG. 11 illustrates a cooperative process between devices;

FIG. 12 illustrates how to collect data regarding a business volume;

FIG. 13 is a flowchart of how to collect data regarding the businessvolume;

FIG. 14 illustrates an example data structure of a data collection tablefor business volumes;

FIG. 15 is a flowchart of how to determine an I/O state of a businessvolume;

FIG. 16 illustrates an example data structure of a knowledge table forbusiness volumes;

FIG. 17 is a flowchart of how to organize knowledge data;

FIG. 18 illustrates an example data structure of an organized knowledgetable in which knowledge data is organized on a knowledge time framebasis;

FIG. 19 illustrates an example data structure of an organized knowledgetable in which knowledge data is organized on a day basis;

FIG. 20 illustrates how to collect data regarding a copy volume;

FIG. 21 is a flowchart of how to collect data regarding the copy volume;

FIG. 22 illustrates an example data structure of a data collection tablefor copy volumes;

FIG. 23 is a flowchart of how to determine an I/O state of a copyvolume;

FIG. 24 illustrates an example data structure of a knowledge table forcopy volumes;

FIG. 25 illustrates an example data structure of an organized knowledgetable in which knowledge data is organized on a knowledge time framebasis;

FIG. 26 illustrates an example data structure of an organized knowledgetable in which knowledge data is organized on a day basis;

FIG. 27 illustrates how to collect data regarding a tape device;

FIG. 28 is a flowchart of how to collect data regarding the tape device;

FIG. 29 illustrates an example data structure of a data collection tablefor tape devices;

FIG. 30 illustrates an example data structure of a copy volume-baseddata table;

FIG. 31 is a flowchart of how to create a knowledge table in the tapedevice;

FIG. 32 illustrates an example data structure of a volume-basedknowledge table;

FIG. 33 illustrates an example data structure of a drive-based knowledgetable;

FIG. 34 is a flowchart of how to retrieve a backup job;

FIG. 35 illustrates an example merged knowledge table in which data ismerged on a knowledge time frame basis;

FIG. 36 illustrates an example of retrieving records with “busy” state;

FIG. 37 illustrates an example of creating a job management table;

FIG. 38 illustrates an example merged knowledge table in which jobnumbers are set;

FIG. 39 illustrates an example data structure of an organized knowledgetable in which knowledge data is organized on a knowledge time framebasis for each copy volume;

FIG. 40 illustrates an example data structure of an organized knowledgetable in which knowledge data is organized on a knowledge time framebasis for each tape drive;

FIG. 41 illustrates an example data structure of an organized knowledgetable in which knowledge data is organized on a day basis for each copyvolume;

FIG. 42 illustrates an example data structure of an organized knowledgetable in which knowledge data is organized on a day basis for each tapedrive;

FIG. 43 is a first diagram illustrating an example matrix;

FIG. 44 is a second diagram illustrating the example matrix;

FIG. 45 is a flowchart of a candidate search process;

FIG. 46 is a flowchart of a candidate filtering search process;

FIG. 47 is a flowchart of a delay target determination process;

FIG. 48 illustrates a procedure of a backup classification process;

FIG. 49 illustrates an example classification of backups;

FIG. 50 is a flowchart of a reschedule proposing process;

FIG. 51 illustrates an example organized knowledge table in whichknowledge data is organized on a knowledge time frame basis for eachcopy volume;

FIG. 52 illustrates an example of searching for an available time;

FIG. 53 illustrates an example proposed schedule table;

FIG. 54 illustrates an example rescheduling of a backup job with jobnumber of “2”;

FIG. 55 is a flowchart of a use drive search process;

FIG. 56 illustrates an example allocation of a use drive;

FIG. 57 illustrates an example report screen for a proposed schedule;and

FIG. 58 illustrates an execution state of response delay.

DESCRIPTION OF EMBODIMENTS

Embodiments of the present invention will now be described withreference to the accompanying drawings, wherein like reference numeralsrefer to like elements throughout.

First Embodiment

FIG. 1 illustrates a configuration of a first embodiment. FIG. 1illustrates an example system that employs a “Disk to Disk to Tape(D2D2T)” backup system in which data to be backed up (backup source) ina disk device is temporarily copied into another disk device, and thenthe copy data is stored in a tape drive.

The illustrated system includes a disk device 1, a tape device 2, and abackup server 3, and an information processing apparatus 4. The backupserver 3 backs up data from the disk device 1 to the tape device 2. Theinformation processing apparatus 4 collects information of data accessesto the disk device 1 and the tape device 2, and the like, and detects abackup being performed.

The disk device 1 includes a plurality of volumes 1 a and 1 b, a backupunit 1 c, a monitoring unit 1 d, and a storage unit 1 e. For example,each of the volumes 1 a and 1 b may be a hard disk drive. Alternatively,a storage system such as a Redundant Arrays of Inexpensive Disks (RAID)system, which is a collection of a plurality of hard disk drives, may beused as one volume 1 a, 1 b. Yet alternatively, logical volumes producedby dividing the storage area of one hard disk drive or RAID system intoa plurality of areas may be used as the volumes 1 a and 1 b.

The backup unit 1 c backs up data from one volume 1 a to the othervolume 1 b. For example, the backup unit 1 c backs up the volume imagesof all data from the volume 1 a to the volume 1 b. In this connection, abackup is a process of reading data from the volume 1 a and writing acopy of the data in the volume 1 b.

The monitoring unit 1 d monitors the state of access to each volume 1 a,1 b, and stores access information indicating the access state in thestorage unit 1 e. The accesses to be monitored include at least accessesfor data read. The storage unit 1 e stores the access information.

The tape device 2 includes a tape drive 2 a and a drive control unit 2b. The tape drive 2 a is capable of reading and writing data to amagnetic tape 7 inserted therein. The magnetic tape 7 is accommodated ina cartridge, for example, and the cartridge accommodating the magnetictape 7 is inserted in the tape drive. In this connection, an open reelmagnetic tape may be used, in which the magnetic tape 7 is notaccommodated in a cartridge.

The drive control unit 2 b receives an operation instruction foroperating the tape drive 2 a from an external device such as the backupserver 3, and operates the tape drive 2 a in accordance with theinstruction. For example, upon receipt of an operation instruction forcausing the tape drive 2 a to write data on the magnetic tape 7, thedrive control unit 2 b supplies the requested data to the tape drive 2 awhich then writes the data on the magnetic tape 7. If receiving aresponse delay instruction from the information processing apparatus 4after receiving an operation instruction but before responding to theoperation instruction, the drive control unit 2 b intentionally delaysresponding to the operation instruction.

The information processing apparatus 4 includes an acquisition unit 4 a,a determination unit 4 b, an instruction unit 4 c, and a scheduling unit4 d.

The acquisition unit 4 a acquires information from the disk device 1 andtape device 2. More specifically, information to be acquired from thedisk device 1 includes access information stored in the storage unit 1e, and start and end information which indicates the start and end of abackup performed between the volumes 1 a and 1 b in the disk device 1and is acquired from the backup unit 1 c.

In addition, the acquisition unit 4 a monitors inputs of operationinstructions to the tape device 2 regarding a backup of data to amagnetic tape in the tape device, and acquires the details of theoperation instructions.

The determination unit 4 b detects the volume 1 b in which a sequentialread was performed, on the basis of access information acquired by theacquisition unit 4 a, and determines the volume 1 b as the backup sourcefor a backup. In addition, the determination unit 4 b acquires accessinformation at the time when an operation instruction is input to thetape device 2, and recognizes that a backup source for a backup to themagnetic tape 7 specified in the operation instruction is the volume 1 bof the disk device 1.

The determination unit 4 b also determines whether the volume 1 b thatis a backup destination for a backup performed by the backup unit 1 c isthe volume 1 b that is a backup source for a backup performed by thebackup server 3.

The instruction unit 4 c instructs the tape device 2 to delay respondingto an operation instruction, on the basis of start and end informationof a backup acquired from the disk device 1. For example, if theoperation instruction is input to the tape device 2 after acquisition ofthe start information and before acquisition of the end information, theinstruction unit 4 c issues a delay instruction requesting a delay of aresponse to the operation instruction, to the drive control unit 2 b ofthe tape device 2. For example, the instruction unit 4 c issues a delayinstruction to the tape device 2 when the backup server 3 performs abackup from the volume 1 b that is a backup destination for a backupbeing performed by the backup unit 1 c.

The scheduling unit 4 d creates an appropriate schedule of backupsrecognized by the determination unit 4 b. For example, the schedulingunit 4 d detects, as a backup execution time, a period between start andend of a sequential read in the volume 1 b of the disk device 1. Then,if a plurality of backups overlaps in execution time, the schedulingunit 4 d creates a backup schedule by changing the execution time of atleast one backup. At this time, the backup execution time is changed toa period during which there is no access to the volume 1 b.

In addition, the scheduling unit 4 d displays the created backupschedule on a terminal device 5 used by an administrator 6. For example,in the case where the terminal device 5 is directly connected to theinformation processing apparatus 4, the scheduling unit 4 d displays thecreated backup schedule on a screen of the terminal device 5. In thecase where the terminal device 5 is connected to the informationprocessing apparatus 4 over a network, the scheduling unit 4 d sends anelectronic mail on the mail address of the administrator 6, therebytransferring the backup schedule to the terminal device 5 via a mailserver. In this case, the administrator 6 opens the received mail on theterminal device 5 to display the backup schedule on the screen of theterminal device 5.

In such the system, when the backup server 3 backs up data from thevolume 1 b of the disk device 1 to the magnetic tape 7 of the tapedevice 2, a sequential read is performed in the volume 1 b in the diskdevice 1. Then, access information indicating the execution of thesequential read in the volume 1 b is stored in the storage unit 1 e bythe monitoring unit 1 d.

The access information stored in the storage unit 1 e is acquired by theacquisition unit 4 a of the information processing apparatus 4. Then, byrecognizing the sequential read performed in the volume 1 b, thedetermination unit 4 b determines the volume 1 b as a backup source. Byanalyzing the state of access to the volume 1 b in the disk device 1 inthis way, the execution state of the backup using the volume 1 b isrecognized. By using a result of comparing the recognized executionstates of backups with the states of accesses in the disk device 1 andtape device 2, efficiency of the backups may be improved.

For example, the tape device 2 may be caused to delay responding to anoperation instruction when the backup server 3 starts a backup from thevolume 1 b to the tape device 2 while a backup is performed between thevolumes 1 a and 1 b in the disk device 1.

More specifically, the acquisition unit 4 a monitors inputs of operationinstructions to the tape device 2 regarding a backup to the magnetictape 7 in the tape device 2. The determination unit 4 b acquires accessinformation at the time when an operation instruction is input to thetape device 2, and determines that a backup source for a backup to themagnetic tape 7 specified in the operation instruction is the volume 1 bof the disk device 1. For example, if a sequential read is performed inthe volume 1 b when an operation instruction for data write is input tothe tape device 2, the volume 1 b is determined as a backup source.

When the backup unit 1 c starts to back up data from the volume 1 a tothe volume 1 b, the acquisition unit 4 a acquires start informationindicating the start of the backup performed between the volumes 1 a and1 b in the disk device 1. The determination unit 4 b then checks thevolume 1 b that is a backup destination for the backup between thevolumes 1 a and 1 b in the disk device 1. That is to say, thedetermination unit 4 b determines whether the volume 1 b that is thebackup destination for the backup is the volume 1 b of the disk device 1that is a backup source for a backup to the magnetic tape 7 specified inan operation instruction input to the tape device 2. If they are thesame volume, the instruction unit 4 c outputs a delay instruction to thetape device 2 for delaying a response to the operation instruction.Then, the drive control unit 2 b of the tape device 2 operates inaccordance with the operation instruction, and after a predetermineddelay time elapses, makes a response to the backup server 3.

Delaying a response to an operation instruction in this way reduces thenumber of data reads per unit time in the volume 1 b which is a backupdestination for the backup between the volumes of the disk device 1.Reducing the number of data reads results in efficient data write in thebackup between the volumes. Improving efficiency of the backup betweenthe volumes suppresses a decrease in processing efficiency of tasksusing the volume 1 a that is a backup source for the backup between thevolumes.

In addition, by using a result of comparing the execution state of abackup with the states of accesses in the disk device 1 and tape device2, an improved plan for a schedule of backups to be performed by thebackup server 3 may be proposed.

More specifically, the scheduling unit 4 d determines a period fromstart to end of a sequential read as a backup execution time. If aplurality of backups overlaps in execution time, the scheduling unit 4 dcreates a backup schedule by changing an execution time of at least onebackup to a period during which there is no access to the backup sourcevolume 1 b. The created backup schedule is displayed on the terminaldevice 5 used by the administrator 6.

With the provided backup schedule specifying appropriate execution timesfor backups, the administrator 6 is able to set an appropriate backupschedule in the backup server 3. In addition, because the backupschedule is created by using the access information of the disk device1, a backup time may be changed to a time frame during which there is noaccess to a backup source volume. That is, the backup server 3 is ableto confirm the current backup schedule, but may not be able to confirmthe state of access to each volume of the disk device 1. The informationprocessing apparatus 4, on the other hand, is able to confirm the stateof existing backups on the basis of the access information of the diskdevice 1, so as to easily confirm the state of access to each volume aswell on the basis of the access information. As a result, inrescheduling, a backup may be scheduled for a period during which thereis no access to a backup source volume, thereby making it possible toimprove the processing efficiency of backups.

By the way, the functions of the information processing apparatus 4illustrated in FIG. 1 is realized by a Central Processing Unit (CPU)performing computing processes, for example.

FIG. 2 illustrates an example hardware configuration of an informationprocessing apparatus employed in the first embodiment. The informationprocessing apparatus 4 is entirely controlled by a CPU 4-1. A RandomAccess Memory (RAM) 4-2 and a plurality of peripheral devices areconnected to the CPU 4-1 via a bus 4-8.

The RAM 4-2 functions as a main memory of the information processingapparatus 4. The RAM 4-2 temporarily stores at least part of OperatingSystem (OS) program and application programs to be executed by the CPU4-1. In addition, the RAM 4-2 stores various data for use in processingof the CPU 4-1.

The peripheral devices connected to the bus 4-8 include a hard diskdrive (HDD) 4-3, a graphics processor 4-4, an input device interface4-5, an optical drive device 4-6, and a communication interface 4-7.

The HDD 4-3 magnetically reads and writes data to an in-built disk, andfunctions as a secondary memory of the information processing apparatus4. The HDD 4-3 stores the OS program, application programs, and variousdata. As a secondary memory, a semiconductor memory device, such as aflash memory, may be used.

The graphics processor 4-4 is connected to a monitor 9 a. The graphicsprocessor 4-4 displays an image on the screen of the monitor 9 a underthe control of the CPU 4-1. As the monitor 9 a, a display device usingCathode Ray Tube (CRT), a liquid crystal display device or the like maybe used.

The input device interface 4-5 is connected to a keyboard 9 b and amouse 9 c, and transfers signals from the keyboard 9 b and mouse 9 c tothe CPU 4-1. The mouse 9 c is one type of pointing devices, and apointing device, touch panel, tablet, touch pad, track ball or the likemay be used instead.

The optical drive device 4-6 reads data from an optical disc 9 d with alaser beam. The optical disc 9 d is a portable recording medium on whichdata is recorded so as to be read using reflected light. Such opticaldiscs 9 d include Digital Versatile Discs (DVD), DVD-RAMS, Compact DiscRead Only Memories (CD-ROM), CD-Recordable (CD-R)/ReWrittable (RW).

The communication interface 4-7 is connected to a network 8, andperforms data communications with the disk device 1 and tape device 2via the network 8.

With such a hardware configuration, the processing functions of thefirst embodiment are realized.

Second Embodiment

The following describes a second embodiment in which efficiency ofbackups in a data backup system using the D2D2T backup method isimproved through cooperation between a disk device and a tape device.

[System Configuration]

FIG. 3 illustrates an example system configuration according to thesecond embodiment. In the second embodiment, a business server 20, abackup server 30, a disk device 100, and a tape device 200 are connectedto each other over a Storage Area Network (SAN) 10.

The business server 20 is a computer that performs various processesusing data stored in the disk device 100. For example, the businessserver 20 accesses a database stored in the disk device 100 in responseto a transaction request from a user, and returns its result to aterminal device used by the user. The business server 20 includes aplurality of Host Bus Adapters (HBA) 21 and 22. The HBAs 21 and 22 areconnected to the SAN 10. The business server 20 is capable of accessingthe disk device 100 via the HBAs 21 and 22.

The backup server 30 backs up data from the disk device 100 to a medium(magnetic tape) mounted in the tape device 200. For example, the backupserver 30 performs backups in accordance with a predetermined schedule.In a backup, the backup server 30 first reads data to be backed up, fromthe disk device 100, and writes the data on the medium mounted in thetape device 200. The backup server 30 includes a plurality of HBAs 31and 32 connected to the SAN 10. The backup server 30 is capable ofaccessing the disk device 100 and tape device 200 via the HBAs 31 and32.

The disk device 100 provides a RAID system with a plurality of hard diskdrives. The disk device 100 includes a plurality of controller modules(CM) 110 and 120. The controller modules 110 and 120 control the RAIDsystem in the disk device 100 in accordance with requests received fromthe business server 20 and backup server 30 via the SAN 10.

The controller module 110 has a channel adaptor (CA) 111 and CPU 112.The channel adaptor 111 is a communication interface for performingcommunications with the business server 20 and backup server 30. The CPU112 manages RAID groups 130-1 and 130-2 connected thereto. The CPU 112also analyzes a request from the business server 20 or backup server 30,and accesses the RAID group 130-1 or 130-2.

The controller module 120 has a channel adaptor 121 and CPU 122. Thechannel adaptor 121 is a communication interface for performingcommunications with the business server 20 and backup server 30. The CPU122 manages the RAID groups 140-1 and 140-2 connected thereto. The CPU122 also analyzes a request from the business server 20 or backup server30, and accesses the RAID group 140-1 or 140-2.

The disk device 100 has a plurality of RAID groups 130-1, 130-2, 140-1,and 140-2. Each RAID group 130-1, 130-2, 140-1, 140-2 is divided into aplurality of logical volumes each given an identifier called LogicalUnit Number (LUN). In the example of FIG. 3, logical volumes that storedata to be accessed from the business server 20 are called businessvolumes 131 and 141. In addition, logical volumes that store a copy ofdata stored in the business volumes 131 and 141 are called copy volumes132 and 142.

In the disk device 100, data in the business volume 131 is copied to thecopy volume 132 in accordance with a predetermined schedule, forexample, at a specified time with snapshot technology. Similarly, datain the business volume 141 is copied to the copy volume 142 inaccordance with the predetermined schedule.

The tape device 200 selects one of a plurality of media, and reads andwrites data to the selected medium. The tape device 200 includes a robot210 and a plurality of tape drives 221, 231, 241, and 251.

The robot 210 takes a media cartridge out of a rack (instrumentationrack) accommodating media, and inserts the cartridge into a tape drive221, 231, 241, or 251. The robot 210 also stores a medium ejected from atape drive 221, 231, 241, or 251 at a specified position of the rack.

The tape drives 221, 231, 241, and 251 read and write data to media. Inthe example of FIG. 3, the tape drives 221 and 231 are based on thefourth-generation Linear Tape-Open (LTO) technology (LTO Ultrium 4). Thetape drives 241 and 251 are based on the third-generation LTO technology(LTO Ultrium 3). In this connection, the fourth-generation technologyrealizes faster data input and output than the third-generationtechnology.

[Summary of Improvement in Efficiency of Backups]

The system illustrated in FIG. 3 improves efficiency of backups. To thisend, for example, a process for providing improvement information for abackup schedule and a delay control process of delaying an operation ofa tape drive at the time of backup are performed.

FIG. 4 illustrates an example backup schedule to be improved. FIG. 4illustrates the execution time frames of backup jobs that are performedin a day. Referring to the example of FIG. 4, “backup job #1” for “LUN1”is executed in a time frame from 00:00 to 08:00. “Backup job #2” for“LUN2” is executed in a time frame from 01:00 to 04:00. “Backup job #3”for “LUN3” is executed in a time frame from 01:00 to 07:00.

According to this schedule, three backup jobs are executed in the timeframe from 01:00 to 04:00. In addition, two backup jobs are executed inthe time frame from 04:00 to 07:00.

Backup data of the disk device 100 is transferred to the tape device 200via the backup server 30. Therefore, if some jobs are executedsimultaneously as illustrated in FIG. 4, a heavy load is placed on thebackup server 30. This fails to make the best use of the performance oftape drives.

In the second embodiment, a tape state monitoring unit 271 of the tapedevice 200 detects a time frame in which some backup jobs are executed,and proposes an improved backup schedule. For example, the tape statemonitoring unit 271 proposes that at least one of a plurality of backupjobs executed simultaneously be executed in another available timeframe. This proposal is given from the tape state monitoring unit 271 toan administrator via an email, for example.

FIG. 5 illustrates an example backup in which delay control for delayingan operation of a tape drive is effective. Referring to the example ofFIG. 5, as the business volumes 401, . . . , 40 n, logical volumes inthe RAID group #1 which realizes fast access are used, placing anemphasis on speed. As the copy volume 410, on the other hand, a largecapacity logical volume provided in one RAID group #2 is used, placingan emphasis on capacity. For example, the RAID group #2 provided withthe copy volume 410 is called a nearline disk drive. A nearline diskdrive refers to a disk device which is not often accessed but is able tobe accessed immediately when needed. Then, data in the plurality ofbusiness volumes 401, . . . , 40 n is backed up to the single copyvolume 410. The backup data stored in the copy volume 410 is then backedup to a plurality of tape drives 421 . . . , 42 n corresponding to therespective backup source business volumes.

In the “Disk to Disk (D2D)”, a large capacity nearline disk device isoften used as an area for backup as illustrated in FIG. 5. Therefore, ann-to-one backup (n is an integer of 1 or greater) is performed, whichresults that an access confliction easily occurs within the RAID group#2 used as a nearline disk device. In addition, if the D2D backup and abackup from a copy volume to a medium overlap, a load of a copy from abusiness volume becomes higher in accordance with a load of reading fromthe copy volume. This is because there occurs an access to data whichhas not been transferred, in the business volume.

In addition, an effective capacity is secured in the RAID 5, as comparedwith the RAID 1. Therefore, in general, a RAID 5 configuration isemployed for the area of a copy volume. However, in the RAID 5, a writeresponse is slower than a read response. As a result, if a backup from abusiness volume to a copy volume and a backup from a copy volume to atape device overlap, a decrease in efficiency of the data transfer tothe tape device is considerable.

Therefore, in the second embodiment, individual operations involved in abackup to the tape device are appropriately delayed while a D2D backupis performed in the disk device 100. This makes it possible to suppressa decrease in processing efficiency due to an access conflict in thecopy volume 410. In this connection, the D2D backup is performed withsnapshot technology. A snapshot is a process of copying all data of abusiness volume to a copy volume at the time of starting the backupwithout interrupting accesses to the business volume.

[Functions Used for Improving Efficiency of Backups]

The following describes the functions of the disk device 100 and tapedevice 200 used for improving efficiency of backups.

The disk device 100 and tape device 200 collect information on dataaccesses to recognize backup operations, organize the collectedinformation, and determine an improved backup schedule and alsodetermine whether to delay an operation of the tape device 200. To doso, the following parameters relating to information accumulation andorganization are previously set in the disk device 100 and tape device200.

[Data Collection Interval]

A data collection interval is an interval at which to monitor businessvolumes, a copy volume, and a tape device (i.e. to collect data). Forexample, a value indicating ten seconds is set.

[Knowledge Period]

A knowledge period is the length of time during which collected data isretained. For example, a value indicating one week is set.

[Knowledge Unit]

A knowledge unit is the length of a time frame for determining a “state(idle/busy)” from collected data. For example, a value indicating onehour is set.

[Threshold]

A threshold is a value for use in determining whether to keep, as arecord, an I/O count indicating the number of I/Os, which is acquired atdata collection intervals. If the I/O count is equal to or greater thanthe threshold, the access count is recorded.

FIG. 6 is a functional block diagram of a disk device. The disk device100 has a plurality of control units 150 and 160, a plurality ofcommunication units 171 to 174, a display unit 175, and a plurality ofdisk drives 181, 182, 183, 184, 185, . . . .

The control unit 150 and communication units 171 and 172 are functionsrealized by the controller module 110. The communication unit 171performs communications with a higher-level device such as the businessserver 20 or backup server 30. The communication unit 172 performscommunications with the tape device 200.

The control unit 150 performs data communications with the businessserver 20 and backup server 30 via the communication unit 171. Thecontrol unit 150 also performs data communications with the tape device200 via the communication unit 172. The control unit 150 also performsdata communications with a terminal device directly connected thereto.

The control unit 150 includes a disk state monitoring unit 151, amanagement table storage unit 152, and a disk control unit 153. The diskstate monitoring unit 151 supports a tape backup in cooperation with thetape device 200. For example, the control unit 150 collects usefulinformation for realizing an efficient tape backup, from the businessvolume 131 and copy volume 132, and sends the information to the tapedevice 200. The management storage unit 152 stores information collectedby the disk state monitoring unit 151. For example, a partial storagearea of the RAM in the controller module 110 is used as the managementtable storage unit 152. The disk control unit 153 accesses the businessvolume or copy volume in accordance with a request from the businessserver 20 or backup server 30. In addition, the disk control unit 153stores a copy of data stored in the business volume 131, in the copyvolume 132 with the “Disk to Disk” technique.

The control unit 160 and communication units 173 and 174 are functionsrealized by the controller module 120. The communication unit 173performs communications with a higher-level device such as the businessserver 20 or backup server 30. The communication unit 174 performscommunications with the tape device 200.

The control unit 160 performs data communications with the businessserver 20 or backup server 30 via the communication unit 173. Thecontrol unit 160 also performs data communications with the tape device200 via the communication unit 174. The control unit 160 also performsdata communications with a terminal device directly connected thereto.

The control unit 160 includes a disk state monitoring unit 161,management table storage unit 162, and disk control unit 163. The diskstate monitoring unit 161 supports a tape backup in cooperation with thetape device 200. For example, the control unit 160 collects usefulinformation for realizing an effective tape backup, from the businessvolume 141 and copy volume 142, and sends the information to the tapedevice 200. The management table storage unit 162 stores informationcollected by the disk state monitoring unit 161. For example, a partialstorage area of a RAM in the controller module 120 is used as themanagement table storage unit 162. The disk control unit 163 stores acopy of data stored in the business volume 141, in the copy volume 142with the “Disk to “Disk” technique.

The display unit 175 displays the state of the disk device 100, and thelike. For example, the display unit 175 displays an error code of anerror detected by the control unit 150, 160.

The disk drives 181, 182, 183, 184, 185, . . . , read and write data tomagnetic disks. The disk device 100 is capable of accommodating diskdrives of different performances. In this case, disk drives that providea faster access speed constitute one RAID group, and the storage area ofthe RAID group may be divided to realize business volumes. In addition,disk drives that provide a larger capacity constitute one RAID group,and the storage area of the RAID group is divided to realize copyvolumes. In the case where the business volume and copy volume arerealized by different RAID groups, a RAID 0+1 system is adopted for theRAID group to which the business volume belongs, whereas a RAID 5 systemis adopted for the RAID group to which the copy volume belongs.

FIG. 7 illustrates example tables stored in a management table storageunit of a disk device. A plurality of management tables is stored in themanagement table storage unit 152. The management tables to be storedare classified into a business volume management table group 152 a and acopy volume management table group 152 b. The business volume managementtable group 152 a is a collection of management tables for managing datacollected from the business volume 131. The copy volume management tablegroup 152 b is a collection of management tables for managing datacollected from the copy volume 132.

The business volume management table group 152 a includes a datacollection table 41, a knowledge table 42, and a plurality of organizedknowledge tables 51, 52, 53, . . . . The data collection table 41 is adata table for storing data collected from the business volume 131. Theknowledge table 42 is a data table in which an I/O state is set for eachpredetermined unit (knowledge unit)-based time frame (knowledge timeframe) on the basis of data set in the data collection table 41. Theorganized knowledge tables 51, 52, 53, . . . are data tables in which aresult of organizing data of the knowledge table 42 on a predeterminedunit time basis is set. For example, a result of organizing data with aperiod of knowledge unit as a unit time is set in the organizedknowledge table 51, and a result of organizing data with one day as aunit time is set in the organized knowledge table 52.

The copy volume management table group 152 b includes a data collectiontable 61, a knowledge table 62, and a plurality of organized knowledgetables 71, 72, 73, . . . . The data collection table 61 is a data tablein which data collected from the copy volume 132 is stored. Theknowledge table 62 is a data table in which a result of organizing datastored in the data collection table 61 on a predetermined unit(knowledge unit) basis is set. The organized knowledge tables 71, 72,73, . . . are data tables in which a result of organizing data of theknowledge table 62 on a predetermined unit time basis is set. Forexample, a result of organizing data with a period of knowledge unit asa unit time is set in the organized knowledge table 71, and a result oforganizing data with one day as a unit time is set in the organizedknowledge table 72.

The following describes the functions of the tape device 200.

FIG. 8 is a functional block diagram of a tape device. The tape device200 has a robot 210, a plurality of drive modules 220, 230, 240, 250, aplurality of communication units 261 and 262, a control unit 270, adisplay unit 282, a rack 283, and an insertion slot 284.

The drive modules 220, 230, 240, and 250 have built-in tape drives 221,231, 241, and 251 illustrated in FIG. 3, and control the built-in tapedrives 221, 231, 241, and 251 for write of data received via the SAN 10to media, and the like.

The communication unit 261 performs communications with a higher-leveldevice such as the business server 20 or backup server 30. Thecommunication unit 262 performs communications with the disk device 100.

The control unit 270, display unit 282, rack 283, and insertion slot 284use the robot 210 to load and unload media in/from the tape drives.

The control unit 270 is a function realized by the CPU and RAM. Thecontrol unit 270 includes a tape state monitoring unit 271, a managementtable storage unit 272, and a library control unit 273.

The tape state monitoring unit 271 controls a data backup from the diskdevice 100 to a medium. The tape state monitoring unit 271 also collectsaccess information such as an operation state of a tape drive. The tapestate monitoring unit 271 communicates with the disk state monitoringunits 151 and 161 of the disk device 100 via the communication unit 262to acquire access information collected by the disk device 100.

Further, the tape state monitoring unit 271 analyzes a “Disk to Tape”backup on the basis of access information acquired from the disk device100 and access information collected by the own unit 271. For example,the tape state monitoring unit 271 detects a backup source copy volumefor the backup on the basis of the data acquired from the disk device100. In addition, for example, when receiving data to be backed up, fromthe backup server 30, the tape state monitoring unit 271 determines acopy volume in the disk device 100 in which a sequential read isperformed, as a backup source volume for a “Disk to Tape” backup. Thetape state monitoring unit 271 also detects a backup destination copyvolume for a “Disk to Disk” backup performed in the disk device 100, onthe basis of the data acquired from the disk device 100.

Then, the tape state monitoring unit 271 determines an efficient backuptime on the basis of the access information acquired from the diskdevice 100 and the access information collected by the own unit 271. Forexample, if backup jobs are executed simultaneously, the tape statemonitoring unit 271 searches for an available time for a backup, andcreates an improved schedule plan by changing the backup execution timeto the available time. The tape state monitoring unit 271 notifies asystem administrator of the improved backup schedule plan via an email,for example. In addition, the tape state monitoring unit 271 delays amedia mounting process, a ready response process, a write process, orthe like on the basis of the access information acquired from the diskdevice 100. The mounting process is a process of causing a system torecognize a storage medium or the like. The ready response process is aprocess of making a notification that a storage medium or the like isready to be accessed.

The management table storage unit 272 stores information collected bythe tape state monitoring unit 271, and the like. For example, a partialstorage area of a RAM in the tape device 200 is used as the managementtable storage unit 272.

The library control unit 273 controls the robot 210 to insert a tapecartridge accommodated in the rack 283 into a tape drive. The librarycontrol unit 273 also controls the robot 210 to accommodate a tapecartridge ejected from a tape drive into the rack 283.

Under the control of the library control unit 273, the robot 210 takes atape cartridge out of the rack 283 with a mechanical arm, carries thetape cartridge to a tape drive, and inserts the tape cartridge into themedia slot of the tape drive. In addition, under the control of thelibrary control unit 273, the robot 210 takes a tape cartridge from themedia slot of a tape drive with the arm, carries the tape cartridge tothe rack 283, and inserts the tape cartridge at a specified position inthe rack 283.

The display unit 282 displays information specified by the librarycontrol unit 273 on a screen. The rack 283 is provided with a pluralityof slots 283 a for accommodating tape cartridges. The insertion slot 284is an opening where a tape cartridge is inserted from outside into therack 283.

FIG. 9 is an example internal configuration of a drive module. The drivemodule 220 includes a tape drive 221 and control unit 222. The tapedrive 221 reads and writes data to a medium in a tape cartridge insertedtherein. The control unit 222 controls the tape drive 221 in accordancewith an access request from a higher-level device.

The other drive modules 230, 240, and 250 may have the same internalconfiguration as the drive module 220 illustrated in FIG. 9.

FIG. 10 illustrates example tables stored in a management table storageunit of a tape device. The management table storage unit 272 includes adata collection table 81, a copy volume-based data table 82, avolume-based knowledge table 83, a drive-based knowledge table 84, a jobmanagement table 85, organized knowledge tables 91, 92, 93, . . . , anda proposed schedule table 310.

The data collection table 81 is a data table in which data collectedfrom tape drives is set. The copy volume-based data tables 82 containonly data on each backup source copy volume extracted from the datacollection table 81. The volume-based knowledge table 83 is a data tablein which a result of extracting and aggregating data on each copy volumefrom the data collection table 81 on a predetermined unit (knowledgeunit) basis is set. The drive-based knowledge table 84 is a data tablein which a result of extracting and aggregating data on each tape drivefrom the data collection table 81 on a predetermined unit (knowledgeunit) basis is set. The job management table 85 is a data table in whichinformation on each backup job is set. Each organized knowledge table91, 92, 93, . . . is a data table in which a result of organizing datastored in the volume-based knowledge table 83 or drive-based knowledgetable 84 under predetermined conditions is set. For example, a result oforganizing the data with a knowledge unit as a unit time for each copyvolume is set in the organized knowledge table 91.

The proposed schedule table 310 is a data table in which an improvedplan for backup jobs is set.

[Outline of Cooperative Process]

The following outlines a cooperative process relating to a backupbetween devices.

FIG. 11 illustrates a cooperative process between devices. The businessserver 20 makes a business-related access (business access) to abusiness volume 131 of the disk device 100. The disk control unit 153 ofthe disk device 100 reads and writes data to the business volume 131 inresponse to the business access. The disk control unit 153 of the diskdevice 100 also backs up data from the business volume 131 to a copyvolume 132 in accordance with an instruction from the backup server 30.In this backup from the business volume 131 to the copy volume 132, asequential read of data from the business volume 131 and a sequentialwrite of the data to the copy volume 132 are performed under the controlof the disk control unit 153.

Such reading and writing to the business volume 131 and copy volume 132are monitored by the disk state monitoring unit 151 in the disk device100. The disk state monitoring unit 151 stores information such as thenumber of accesses in the management table storage unit 152. Inaddition, when a backup from the business volume 131 to the copy volume132 starts, the disk state monitoring unit 151 notifies the tape device200 of the start of the D2D backup.

The backup server 30 sends the disk device 100 an instruction for abackup from the business volume to the copy volume, in accordance with apredetermined schedule. In addition, the backup server 30 performs abackup from the copy volume 132 of the disk device 100 to the tapedevice 200 in accordance with a predetermined schedule. In this case,the backup server 30 performs backup read from the copy volume 132 ofthe disk device 100. At this time, the disk control unit 153 of the diskdevice 100 performs a sequential read on the copy volume 132, and sendsthe read data to the backup server 30. The backup server 30 temporarilystores the data acquired from the disk device 100 through the backupread, in an internal memory.

After that, the backup server 30 performs backup write to the tapedevice 200. At this time, the library control unit 273 of the tapedevice 200 instructs the robot 210 to perform a media mountingoperation. The robot 210 operates as instructed. When a mediumaccommodated in the tape drive 221 gets ready to write data thereonthrough a series of operations including the media mounting, the librarycontrol unit 273 of the tape device 200 notifies the backup server 30 ofthis state. Then, the backup server 30 sends data to be backed up, tothe tape device 200. In the tape device 200, the tape drive 221 writesthe data received from the backup server 30, on the medium mountedtherein. When the writing of data to be backed up is completed, thelibrary control unit 273 unmounts the medium. The unmounting is aprocess for excluding a medium from being monitored in this system.

Backup-related operations of the tape drives 221 and 231 and robot 210are monitored by the tape state monitoring unit 271. The tape statemonitoring unit 271 stores information obtained through the monitoring,in the management table storage unit 272. In addition, the tape statemonitoring unit 271 consults the management table storage unit 152 ofthe disk device 100 to check the state of access to the disk device 100at predetermined timing.

[Details of Process of Collecting and Organizing Data Regarding BusinessVolume]

The following describes a process of collecting and organizinginformation indicating the state of access to a business volume.

FIG. 12 illustrates how to collect data regarding a business volume. Abusiness access from the business server 20 is acknowledged by the diskcontrol unit 153 of the disk device 100. The disk control unit 153 makesan I/O request for reading or writing to the business volume 131 inresponse to the business access, and receives its response. Then, thedisk control unit 153 sends a result of accessing the business volume131 to the business server 20.

At this time, I/O operations to the business volume 131 are monitored bythe disk state monitoring unit 151. Then, the disk state monitoring unit151 stores the state of the I/O operations to the business volume 131,in the management table storage unit 152.

FIG. 13 is a flowchart of how to collect data regarding a businessvolume. This data collection process of FIG. 13 will be describedstep-by-step.

At operation S11, the disk state monitoring unit 151 acquires an I/Ocount indicating the number of I/Os to each business volume at datacollection intervals.

At operation S12, the disk state monitoring unit 151 determines whetheror not the acquired I/O count is equal to or greater than apredetermined threshold. If this determination is affirmative, the diskstate monitoring unit 151 proceeds to operation S13; otherwise, the diskstate monitoring unit 151 proceeds to operation S14.

At operation S13, the disk state monitoring unit 151 stores the acquiredI/O count for a corresponding data collection time frame in the datacollection table 41 of the business volume management table group 152 a.Then, the disk state monitoring unit 151 proceeds to operation S15.

At operation S14, the disk state monitoring unit 151 sets “0” as the I/Ocount for a corresponding data collection time frame in the datacollection table 41 of the business volume management table group 152 a.

At operation S15, the disk state monitoring unit 151 determines whetheran elapsed time counted from the start of registering data in the firstrecord in the data collection table 41 reaches one day. If thisdetermination is affirmative, the disk state monitoring unit 151proceeds to operation S16; otherwise, the disk state monitoring unit 151proceeds back to operation S11.

At operation S16, the disk state monitoring unit 151 moves from thecurrent record to the first record of the data collection table 41 forthe data collection, and proceeds back to operation S11. At this time,the elapsed time is reset to “0”.

As described above, an I/O count is recorded at data collectionintervals in the data collection table 41. The process of FIG. 13 isexecuted for each business volume.

FIG. 14 illustrates an example data structure of a data collection tablefor business volumes. The data collection table 41 has fields for DataCollection Time Frame, and I/O Count for each business volume.

The Data Collection Time Frame field indicates a time frame (datacollection time frame) obtained by dividing one day by a data collectioninterval. Referring to the example of FIG. 14, a data collectioninterval is 10 seconds, and time frames of 10 seconds from 00:00 to24:00 in a day are set as data collection time frames. A valueindicating a data collection time frame is represented by a time elapsedfrom 00:00 in seconds.

The I/O Count field for each business volume indicates an I/O countindicating the number of I/Os to the business volume for a correspondingdata collection time frame in association with the identification number(LUN) of the business volume of the disk device 100.

On the basis of such the data collection table 41, an I/O state for eachknowledge time frame obtained by dividing a knowledge period by aknowledge unit is determined, and the determination result is registeredin the knowledge table 42.

FIG. 15 is a flowchart of how to determine an I/O state of a businessvolume. This state determination process of FIG. 15 will be describedstep-by-step.

At operation S21, the disk state monitoring unit 151 sequentially addsthe I/O counts of a business volume in order from the first one ofrecords falling within a knowledge unit-based period (knowledge timeframe) in the data collection table 41. More specifically, when data fora knowledge time frame (for example, for one hour) is registered in thedata collection table 41, the disk state monitoring unit 151 adds theI/O counts corresponding to the data collection time frames fallingwithin the knowledge time frame in question.

At operation S22, the disk state monitoring unit 151 determines whetherthe addition result is “0” or not. If this determination is affirmative,the disk state monitoring unit 151 proceeds to operation S23; otherwise,the disk state monitoring unit 151 proceeds to operation S24.

At operation S23, the disk state monitoring unit 151 sets “idle” for theknowledge time frame in question in the knowledge table 42. Then, thedisk state monitoring unit 151 proceeds to operation S25.

At operation S24, the disk state monitoring unit 151 sets “busy” for theknowledge time frame in question in the knowledge table 42.

At operation S25, the disk state monitoring unit 151 determines whetherthe aggregation for a knowledge period (for example, for one week) hasbeen completed or not. If this determination is affirmative, the diskstate monitoring unit 151 proceeds to operation S26; otherwise, the diskstate monitoring unit 151 proceeds back to operation S21.

At operation S26, the disk state monitoring unit 151 changes the dataaggregation day to the first day of the knowledge period. For example,assume that the knowledge period is one week from Monday to Sunday. Whenthe aggregation for Sunday is completed, the next aggregation day is setto Monday.

As described above, the data aggregated from the data collection table41 is registered in the knowledge table 42.

FIG. 16 illustrates an example data structure of a knowledge table forbusiness volumes. The knowledge table 42 has fields for Day of KnowledgePeriod, Knowledge Time Frame, and I/O State for each business volume.

The Day of Knowledge Period field indicates a day of a knowledge period.The Knowledge Time Frame field indicates a time frame (knowledge timeframe) obtained by dividing a knowledge period by a knowledge unit. TheI/O State field for each business volume indicates an I/O state of thebusiness volume for a corresponding knowledge time frame in associationwith the identification number (LUN) of the business volume of the diskdevice 100. As an I/O state, “idle” or “busy” is set.

Data (knowledge data) set in the knowledge table is organized on aknowledge time frame basis or on a day basis. For example, the knowledgedata is organized when a knowledge period elapses.

FIG. 17 is a flowchart of how to organize knowledge data. This knowledgedata organization process of FIG. 17 will be described step-by-step.

At operation S31, the disk state monitoring unit 151 consults theknowledge table 42 to select knowledge time frames for state merging. Ifknowledge data is organized on a knowledge time frame basis, the diskstate monitoring unit 151 selects the same knowledge time frame of eachday for the state merging. If knowledge data is organized on a daybasis, the disk state monitoring unit 151 selects the knowledge timeframes of the same day for the state merging.

At operation S32, the disk state monitoring unit 151 determines whetherthe states corresponding to the knowledge time frames selected for themerging are all “idle” or not. If all of the states are “idle”, the diskstate monitoring unit 151 proceeds to operation S33. If the statecorresponding to at least one of the knowledge time frames is “busy”,the disk state monitoring unit 151 proceeds to operation S34.

At operation S33, the disk state monitoring unit 151 sets “idle” as amerging result in an organized knowledge table. Then, the disk statemonitoring unit 151 proceeds to operation S35.

At operation S34, the disk state monitoring unit 151 sets “busy” as amerging result in the organized knowledge table.

At operation S35, the disk state monitoring unit 151 determines whetherthere are any knowledge time frames unselected for the state merging.For example, if all of the knowledge time frames in the knowledge table42 were selected at operation S31, the disk state monitoring unit 151determines that the merging has been completed for the knowledge timeframes, and completes this process. If there is any knowledge time frameunselected for the state merging, on the contrary, the disk statemonitoring unit 151 proceeds back to operation S31.

FIG. 18 illustrates an example data structure of an organized knowledgetable in which knowledge data is organized on a knowledge time framebasis. The organized knowledge table 51 has fields for Knowledge Period,Knowledge Time Frame, and I/O State for each business volume.

The Knowledge Period field indicates a knowledge period. Referring tothe example of FIG. 18, one week from Monday to Sunday is set as aknowledge period. The Knowledge Time Frame field indicates a knowledgetime frame. Referring to the example of FIG. 18, 24 time frames of onehour, which are obtained by dividing one day by one hour (knowledgeunit), are set. The I/O State field for each business volume indicates amerging result of I/O states of the business volume for a correspondingknowledge time frame.

For example, the organized knowledge table 51 indicates that thebusiness volume “LUN0” has an I/O state of “idle” for a knowledge timeframe of “00-01” (00:00 to 01:00). This means that I/O operationsexceeding the threshold were not performed between 00:00 to 01:00 in anyday. In addition, the organized knowledge table 51 indicates that thebusiness volume “LUN0” has an I/O state of “busy” for a knowledge timeframe of “07-08” (07:00 to 08:00). This means that I/O operationsexceeding the threshold were performed between 07:00 and 08:00 in atleast one day of the knowledge period.

FIG. 19 illustrates an example data structure of an organized knowledgetable in which knowledge data is organized on a day basis. The organizedknowledge table 52 has fields for Day, and I/O State for each businessvolume. The Day field indicates a day of a knowledge period. The I/OState field for each business volume indicates a merging result of I/Ostates of the business volume for a corresponding day.

For example, the organized knowledge table 52 indicates that thebusiness volume “LUN0” has an I/O state of “busy” for Monday. This meansthat I/O operations to the business volume of “LUN0” which exceed thethreshold were performed for at least one hour on Monday. In addition,the organized knowledge table 52 indicates that the business volume“LUN2” has an I/O state of “idle” for Monday. This means that, onMonday, there is no knowledge time frame in which I/O operations exceedthe threshold.

[Process of Collecting and Organizing Data Regarding Copy Volume]

The following describes how to collect and organize informationindicating the state of access to a copy volume.

FIG. 20 illustrates how to collect data regarding a copy volume. Aninstruction for a D2D backup is issued from the backup server 30 to thedisk device 100. Then, the disk control unit 153 of the disk device 100establishes a session with the copy volume 132 in response to the D2Dbackup instruction. Then, the disk control unit 153 reads data from thebusiness volume 131 and backs up the data to the copy volume 132 withthe “Disk to Disk” technique. When this backup is completed, the diskcontrol unit 153 disconnects the session.

In addition, to start a backup job, the backup server 30 makes a requestfor reading data from the copy volume 132 (data read request), to thedisk device 100. Then, the disk control unit 153 of the disk device 100reads data from the copy volume 132, and sends the data to the backupserver 30.

The state of I/O accesses from the disk control unit 153 to the copyvolume 132 is monitored by the disk state monitoring unit 151. Forexample, the disk state monitoring unit 151 monitors I/O operations tothe copy volume 132 to accumulate the I/O counts in the management tablestorage unit 152. In addition, the disk state monitoring unit 151detects a session establishment/disconnection for a D2D backup, andnotifies the tape device 200 of this matter. The session establishmentand disconnection indicate start and end of a D2D backup, respectively.For example, a notification of session establishment or disconnectionincludes the identification number of a copy volume which is a backupdestination of a D2D backup which is started or ended.

FIG. 21 is a flowchart of how to collect data regarding a copy volume.This data collection process of FIG. 21 will be described step-by-step.

At operation S41, the disk state monitoring unit 151 acquires the numberof accesses in sequential access to each copy volume for each of readingand writing, at data collection intervals. The sequential access is aset of successive accesses to successive storage areas of a disk device.Sequential access for writing data in successive areas is specificallycalled a sequential write. Sequential access for reading data fromsuccessive areas is specifically called a sequential read.

An I/O count in sequential access is counted in such a manner that theI/O count is 10 if 10 inputs and/or outputs are made in the sequentialaccess.

At operation S42, the disk state monitoring unit 151 determines whetherthe I/O count acquired at data collection intervals is equal to orgreater than a predetermined threshold. If this determination isaffirmative, the disk state monitoring unit 151 proceeds to operationS43; otherwise, the disk state monitoring unit 151 proceeds to operationS44.

At operation S43, the disk state monitoring unit 151 stores the acquiredI/O count for a corresponding data collection time frame in the datacollection table 61 of the copy volume management table group 152 b.Then, the disk state monitoring unit 151 proceeds to operation S45.

At operation S44, the disk state monitoring unit 151 sets “0” as the I/Ocount for a corresponding data collection time frame in the datacollection table 61 of the copy volume management table group 152 b.

At operation S45, the disk state monitoring unit 151 determines whetheran elapsed time counted from the start of registering data in the firstrecord of the data collection table 61 reaches one day. If thisdetermination is affirmative, the disk state monitoring unit 151proceeds to operation S46; otherwise, the disk state monitoring unit 151proceeds back to operation S41.

At operation S46, the disk state monitoring unit 151 moves from thecurrent record to the first record of the data collection table 61 forthe data collection, and proceeds back to operation S41. At this time,an elapsed time is reset to “0”.

As described above, an I/O count is registered at data collectionintervals in the data collection table 61. The process of FIG. 21 isperformed for each copy volume.

FIG. 22 illustrates an example data structure of a data collection tablefor copy volumes. The data collection table 61 has fields for DataCollection Time Frame, and I/O Count for each copy volume.

The Data Collection Time Frame field indicates a time frame (datacollection time frame) obtained by dividing one day by a data collectioninterval. Referring to the example of FIG. 22, a data collectioninterval is 10 seconds, and time frames of 10 seconds in a day from00:00 to 24:00 are set as data collection time frames. A valueindicating a data collection time frame is represented by an elapsedtime counted from 00:00 in seconds.

The I/O Count field for each copy volume indicates a I/O count persecond for each of data read and write to the copy volume, for acorresponding data collection time frame in association with theidentification number (LUN) of the copy volume of the disk device 100.

On the basis of such the data collection table 61, start and end of a“Disk to Disk (D2D)” backup and start and end of a “Disk to Tape (D2T)”backup are recognized.

Assume now that there are data collection time frames in which one ormore I/O operations for writing were executed after a data collectiontime frame having an I/O count of “0” for writing. This means that a D2Dbackup started in the first one of the data collection time frames inwhich the one or more I/O operations for writing were performed. On theother hand, assume that there is a data collection time frame with anI/O count of “0” for writing after data collection time frames with anI/O count of one or more for writing. This means that a D2D backup iscompleted in the last one of the data collection time frames in whichthe one or more I/O operations for writing were performed.

In addition, assume that there are data collection time frames in whichone or more I/O operations were performed for reading after a datacollection time frame with an I/O count of “0” for reading. This meansthat a D2T backup is started in the first one of the data collectiontime frames in which the one or more I/O operations for reading wereperformed. Assume that there is a data collection time frame with an I/Ocount of “0” for reading after data collection time frames with an I/Ocount of one or more for reading. This means that a D2T backup iscompleted in the last one of the data collection time frames in whichthe one or more I/O operations for reading were performed.

On the basis of such the data collection table 61, an I/O state for eachknowledge time frame obtained by dividing a knowledge period by aknowledge unit is determined, and the determination result is registeredin the knowledge table 62.

FIG. 23 is a flowchart of how to determine an I/O state of a copyvolume. This I/O state determination process of FIG. 23 will bedescribed step-by-step.

At operation S51, the disk state monitoring unit 151 sequentially addsthe numbers of writes of a copy volume in order from the first one ofrecords falling within a knowledge unit-based time frame (knowledge timeframe) in the data collection table 61. More specifically, when data fora knowledge time frame (for example, for one hour) is registered in thedata collection table 61, the disk state monitoring unit 151 adds thenumbers of writes corresponding to the data collection time framesfalling within the knowledge time frame in question.

At operation S52, the disk state monitoring unit 151 determines whetherthe addition result is “0” or not. If this determination is affirmative,the disk state monitoring unit 151 proceeds to operation S53; otherwise,the disk state monitoring unit 151 proceeds to operation S54.

At operation S53, the disk state monitoring unit 151 sets “idle” for theknowledge time frame in question in the knowledge table 62. Then, thedisk state monitoring unit 151 proceeds to operation S55.

At operation S54, the disk state monitoring unit 151 sets “busy” for theknowledge time frames in question in the knowledge table 62.

At operation S55, the disk state monitoring unit 151 determines whetherthe aggregation for a knowledge period (for example, for one week) hasbeen completed or not. If this determination is affirmative, the diskstate monitoring unit 151 proceeds to operation S56; otherwise, the diskstate monitoring unit 151 proceeds back to operation S51.

At operation S56, the disk state monitoring unit 151 changes the dataaggregation day to the first day of the knowledge period. For example,assume that a knowledge period is one week from Monday to Sunday. Inthis case, the data aggregation for Sunday is completed, the nextaggregation day is set to Monday.

As described above, the data aggregated from the data collection table61 is registered in the knowledge table 62.

FIG. 24 illustrates an example data structure of a knowledge table forcopy volumes. The knowledge table 62 has fields for Day of KnowledgePeriod, Knowledge Time Frame, and I/O State for each copy volume.

The Day of Knowledge Period field indicates a day of a knowledge period.The Knowledge Time Frame field indicates a time frame (knowledge timeframe) obtained by dividing a knowledge period by a knowledge unit. TheI/O State field for each copy volume indicates the I/O state of the copyvolume for a corresponding knowledge time frame in association with theidentification number (LUN) of the copy volume of the disk device 100.As an I/O state, “idle” or “busy” is set.

On the basis of the I/O state of each copy volume for each knowledgetime frame, an execution time of a D2D backup is recognized. Forexample, the example of FIG. 24 indicates that a D2D backup to a copyvolume of “LUN0” is executed between 07:00 and 08:00 and between 08:00and 09:00 on Monday.

Data (knowledge data) set in the knowledge table is organized on aknowledge time frame basis or on a day basis. The knowledge data isorganized when a knowledge period elapses, for example. A process oforganizing knowledge data of a copy volume is performed in the same wayas the process illustrated in FIG. 17 for the knowledge data of abusiness volume.

FIG. 25 illustrates an example data structure of an organized knowledgetable in which knowledge data is organized on a knowledge time framebasis. The organized knowledge table 71 has fields for Knowledge Period,Knowledge Time Frame, and I/O State for each copy volume.

The knowledge Period field indicates a knowledge period. The KnowledgeTime Frame field indicates a knowledge time frame. The I/O State fieldfor each copy volume indicates a result of merging I/O states of thecopy volume for a corresponding knowledge time frame.

For example, the organized knowledge table 71 indicates a copy volume of“LUN0” has an I/O state of “idle” in the knowledge time frame of “00-01”(00:00 to 01:00). This means that a D2D backup was not performed between00:00 and 01:00 on any day of the knowledge period. In addition, theorganized knowledge table 71 indicates that the copy volume of “LUN0”has an I/O state of “busy” in a knowledge time frame of “07-08” (07:00to 08:00). This means that a D2D backup was performed between 07:00 and08:00 on at least one day in the knowledge period.

FIG. 26 illustrates an example data structure of an organized knowledgetable in which knowledge data is organized on a day basis. The organizedknowledge table 72 has fields for Day, and I/O State for each copyvolume. The Day field indicates a day of a knowledge period. The I/OState field for each copy volume indicates a merged I/O state for acorresponding day, for the copy volume.

For example, the organized knowledge table 72 indicates that a copyvolume of “LUN0” has an I/O state of “busy” for Monday. This means thata D2D backup to the copy volume of “LUN0” was performed on Monday. Inaddition, the organized knowledge table 72 indicates that a copy volumeof “LUN1” has an I/O state of “idle” for Monday. This means that a D2Dbackup to the copy volume of “LUN1” was not performed on Monday.

[Collection and Organization of Data Regarding Tape Device]

The following describes how to collect and organize informationindicating the state of access to the tape device 200.

FIG. 27 illustrates a process of collecting data regarding a tapedevice. To back up data from the copy volume 132 to a mediumaccommodated in the tape device 200, the backup server 30 notifies thetape device 200 of media mounting and media allocation as an instructionfor starting the backup. Upon receipt of the media mountingnotification, the library control unit 273 of the tape device 200inserts a medium in a tape drive specified by this notification to mountthe medium, so that the mounted medium becomes ready to be accessed fromthe system. Upon receipt of the media allocation notification, thelibrary control unit 273 allocates the tape drive for the backup job.Allocation is a process for making a tape drive having a medium insertedtherein operable only in a specified job. After the allocation, the tapedrive enters the “ready” state, and the tape device 200 makes a responseof “ready” to the backup server 30. After that, in the backup job of thebackup server 30, a write notification is sent to the allocated tapedrive of the tape device 200.

In addition, the tape state monitoring unit 271 monitors the librarycontrol unit 273, recognizes the media mounting operation as “job start”relating to the backup job, and stores data indicating the job start inthe management table storage unit 272. The tape state monitoring unit271 also acquires data collected by the disk device 100, and detects thecopy volume 132 in which a sequential read has started in the backupjob, on the basis of the acquired data.

When the backup starts, the backup server 30 reads data from the copyvolume 132 of the disk device 100. Then, the backup server 30 instructsthe tape device 20 to write the read data. The tape device 200 writesthe data on the medium under the control of the library control unit273. The tape state monitoring unit 271 monitors a set of write commandsissued from the backup server 30, and stores the backup job informationin the management table storage unit 272.

When the data write is completed, the backup server 30 notifies the tapedevice 200 of a media unmounting operation as a backup end instruction.The library control unit 273 of the tape device 200 unmounts the mediumused in the backup in response to the media unmounting notification. Atthis time, the tape state monitoring unit 271 monitors the librarycontrol unit 273, recognizes the media unmounting operation as “job end”relating to the backup job, and stores data indicating the job end inthe management table storage unit 272.

FIG. 28 is a flowchart of how to collect data regarding a tape drive.This data collection process of FIG. 28 will be described step-by-step.

At operation S61, the tape state monitoring unit 271 sets an initialstate as the state of a tape drive in a current record in question fordata collection in the data collection table 81. For example, assumethat the current record for the data collection is the first record ofthe data collection table 81, the tape state monitoring unit 271 sets“idle” as the state of the tape drive. If the current record for thedata collection is a second or subsequent record of the data collectiontable 81, the tape state monitoring unit 271 sets the state of the tapedrive stored in the previous record, which is a record one before thecurrent record, as the state of the tape drive in the current record.For example, assume that the tape drive has a “backup” state when thedata collection interval for the previous record elapses, this “backup”state is set as the initial state of the tape drive for the currentrecord.

At operation S62, the tape state monitoring unit 271 determines acollection procedure from a matrix according to the details of anotification received from the disk device 100 or backup server 30 andthe state of the tape drive of the time when the tape drive receives thenotification. The matrix defines collection procedures based on statesand notifications. The matrix and collection procedures defined in thematrix will be described later (with reference to FIGS. 43 and 44).

At operation S63, the tape state monitoring unit 271 collects data inaccordance with the collection procedure determined at operation S62.This data collection process will be described in detail later (withreference to FIGS. 45 to 47).

At operation S64, the tape state monitoring unit 271 determines whetherthe data collection interval has elapsed after the current record wastaken as a record in question for the data collection. If the datacollection interval has elapsed, the tape state monitoring unit 271proceeds to operation S65; otherwise, the tape state monitoring unit 271proceeds back to operation S62.

At operation S65, the tape state monitoring unit 271 moves from thecurrent record to the next record of the data collection table 81 forthe data collection.

At operation S66, the tape state monitoring unit 271 determines whetheran elapsed time counted from the start of registering data in the firstrecord of the data collection table 81 has reached one day. The tapestate monitoring unit 271 proceeds to operation S67 if the elapsed timehas reached one day; otherwise, the tape state monitoring unit 271proceeds back to operation S61.

At operation S67, the tape state monitoring unit 271 moves from thecurrent record to the first record of the data collection table 81 forthe data collection, and proceeds back to operation S61. At this time,the elapsed time is reset to “0”.

FIG. 29 illustrates an example data structure of a data collection tablefor tape devices. The data collection table 81 has fields for DataCollection Time Frame, and for each tape drive, State, Write Count,Candidate Copy Volume, Slot (Medium), and D2D Backup Destination CopyVolume.

The Data Collection Time Frame field indicates a time frame (datacollection interval) obtained by dividing one day by a data collectioninterval.

The State field for each tape drive indicates the state of the tapedrive for a corresponding data collection time frame. As a state,“idle”, “mount”, “ready”, “backup”, “mount delay”, “ready delay”, “writedelay”, or “backup delay” is set. An “idle” state indicates an unusedstate. A “mount” state indicates a state where a medium is mounted inthe system. A “ready” state indicates a state where a read command orwrite command is acceptable. A “backup” state indicates a state wheredata is being written in a backup job. A “mount delay” state indicates astate where a tape drive is not used and a tape mounting operation maybe delayed at the time of transition to the “mount” state. A “readydelay” state is a state where a medium is mounted in the system and anoperation of transitioning to a state (“ready” state) in which a read orwrite command is acceptable may be delayed. A “write delay” stateindicates a state where a read or write command is acceptable (“ready”state) and a process of writing data in accordance with a write requestmay be delayed. A “backup delay” state indicates a state where data isbeing written in a backup job (“backup” state) but an operation ofwriting data in accordance with a write request may be delayed.

The Write Count field for each tape drive indicates a write countindicating the number of writes executed in a corresponding datacollection time frame.

The Candidate Copy Volume field for each tape drive indicates theidentification number (LUN) of a copy volume (candidate copy volume)which may be a backup source in a backup job executed in a correspondingdata collection time frame.

The Slot field for each tape drive indicates the identification number(slot number) of a slot having inserted therein a medium on which datawas written in a corresponding data collection time frame.

The D2D Backup Destination Copy Volume field for each tape driveindicates the identification number of a copy volume that was a backupdestination for a D2D backup performed in a corresponding datacollection time frame.

Referring to the example of FIG. 29, in a tape drive with a drive ID of“G4_(—)02”, a medium was mounted in ten seconds from “04:00:00” to“04:00:10” in response to a media mounting notification. The medium wasallocated in ten seconds from “04:00:10” to “04:00:20” in response to anallocation notification. A backup was started to write data in responseto a write notification in ten seconds from “04:00:20” to “04:00:30”. Abackup was executed but data was not written in response to the writenotification in ten seconds from “04:00:30” to “04:00:40”. Data wasoccasionally written thereafter, and the medium was unmounted inresponse to a media unmounting notification in ten seconds from“05:59:50” to “06:00:00”.

In this connection, the reason why data was not written during thebackup, for example, in ten seconds from “04:00:30” to “04:00:40”, isbecause data read from a copy volume is slower than data write to thetape device 200.

Referring to the data collection table 81, candidate copy volumes for abackup are narrowed down as the backup progresses. Referring to theexample of FIG. 29, only a copy volume of “LUN0” is registered as acandidate copy volume in all of the data collection time frames during aperiod from the media mounting notification to the media unmountingnotification. Therefore, the copy volume of “LUN0” is recognized as abackup source volume.

In addition, a session establishment notification indicating the startof a D2D backup using the copy volume of “LUN0” as a backup destinationis received in 10 seconds from “04:01:00” to “04:01:10”. As a result,“LUN0” is set as a D2D backup destination LUN for data collection timeframes after “04:01:00”. Then, in ten seconds from “05:59:40” to“05:59:50”, a session disconnection notification indicating the end ofthe D2D backup using the copy volume of “LUN0” as a backup destinationis received. As a result, the D2D backup destination LUN is not set fordata collection time frames after “05:59:50”. Therefore, the tape statemonitoring unit 271 is able to recognize a backup destination copyvolume for a D2D backup executed in each data collection time frame bychecking the D2D Backup Destination Copy Volume field.

When data for one day is registered in the data collection table 81, thetape state monitoring unit 271 detects a backup source copy volume fromthe data collection table 81. Then, the tape state monitoring unit 271creates a data table for each backup source copy volume (copyvolume-based data table).

FIG. 30 illustrates an example data structure of a copy volume-baseddata table. The copy volume-based data table 82 has fields for DataCollection Time Frame, and for each backup source copy volume, State,Write Count, and Slot (Medium).

The Data Collection Time Frame field indicates a time frame (datacollection time frame) obtained by dividing one day by a data collectioninterval.

The State field for each backup source copy volume indicates the stateof the backup source copy volume. A “busy” state is set during a periodfrom start to end of a backup, and an “idle” state is set during aperiod other than the backup time.

The Write Count field for each backup source copy volume indicates thenumber of writes of data of the copy volume by a tape drive in a backup.

The Slot field for each backup source copy volume indicates the slotnumber of a slot having inserted therein a backup destination medium forthe backup of data of the copy volume.

On the basis of such the copy volume-based data table 82, a knowledgetable for copy volumes (volume-based knowledge table 83) is created.

FIG. 31 is a flowchart of how to create a knowledge table in a tapedrive. This knowledge table creation process of FIG. 31 will bedescribed step-by-step.

At operation S71, the tape state monitoring unit 271 sequentially addsthe I/O counts of a copy volume in order from the first one of recordsfalling within a knowledge unit-based period (knowledge time frame) inthe copy volume-based data table 82. More specifically, when data for aknowledge time frame (for example, for one hour) is registered in thecopy volume-based data table 82, the tape state monitoring unit 271 addsthe write counts corresponding to the data collection time framesfalling within the knowledge time frame in question.

At operation S72, the tape state monitoring unit 271 determines whetherthe states corresponding to the data collection time frames fallingwithin the knowledge time frame in question are all “idle” or not. Ifthis determination is affirmative, the tape state monitoring unit 271proceeds to operation S73. If there is any data collection time framewith a “busy” state, the tape state monitoring unit 271 proceeds tooperation S74.

At operation S73, the tape state monitoring unit 271 sets a job state of“idle” for the knowledge time frame in question in the volume-basedknowledge table 83. Then, the tape state monitoring unit 271 proceeds tooperation S75.

At operation S74, the tape state monitoring unit 271 sets a job state of“busy” for the knowledge time frame in question in the volume-basedknowledge table 83.

At operation S75, the tape state monitoring unit 271 sets a write count,backup time, and slot of the copy volume for the knowledge time frame inquestion in the volume-based knowledge table 83.

At operation S76, the tape state monitoring unit 271 determines whetherthe aggregation for the knowledge period (for example, for one week) hasbeen completed or not. If this determination is affirmative, the tapestate monitoring unit 271 proceeds to operation S77; otherwise, the tapestate monitoring unit 271 proceeds back to operation S71.

At operation S77, the tape state monitoring unit 271 changes the dataaggregation day to the first day of the knowledge period. Assume thatthe knowledge period is one week from Monday to Sunday. In this case,when the data aggregation for Sunday is completed, the next aggregationday is set to “Monday”.

As described above, data aggregated from the copy volume-based datatable 82 is registered in the volume-based knowledge table 83.

FIG. 32 illustrates an example data structure of a volume-basedknowledge table. The volume-based knowledge table 83 has fields for Dayof Knowledge Period, Knowledge Time Frame, and for each copy volume, JobState, Write Count, Backup Time, and Slot (Medium).

The Day of Knowledge Period field indicates a day of a knowledge period.The Knowledge Time Frame field indicates a time frame (knowledge timeframe) obtained by dividing a knowledge period by a knowledge unit.

The Job State field for each copy volume indicates the state of the copyvolume for a corresponding knowledge time frame. A job state of “busy”is set for a copy volume which has a state of “busy” at least once in aknowledge time frame.

The Write Count field for each copy volume indicates the number ofwrites of data read from the copy volume to a tape device in theknowledge time frame.

The Backup Time field for each copy volume indicates the length of timea backup of data of the copy volume was performed, in the knowledge timeframe.

The Slot field for each copy volume indicates a slot having insertedtherein a backup destination medium for a backup of the data of the copyvolume.

In addition, the tape state monitoring unit 271 creates a tapedrive-based knowledge table (drive-based knowledge table 84) almost inthe same way as the process of FIG. 31. However, in creating thedrive-based knowledge table 84, operations S71 and S75 of the flowchartof FIG. 31 are skipped.

FIG. 33 illustrates an example data structure of a drive-based knowledgetable. The drive-based knowledge table 84 has fields for Day ofKnowledge Period, Knowledge Time Frame, and JOB state for each tapedrive.

The Day of Knowledge Period field indicates a day of a knowledge period.The Knowledge Time Frame field indicates a time frame (knowledge timeframe) obtained by dividing a knowledge period by a knowledge unit. TheJob State field for each tape drive indicates the state of a backup jobin which data is backed up to the tape drive in a correspondingknowledge time frame. A job state of “busy” is set if a backup job has a“busy” state at least once in the knowledge time frame.

In the example of FIG. 33, information on tape drives is arranged fromleft to right in order of priority in the drive-based knowledge table84. Referring to the example of FIG. 33, a smaller value represents ahigher priority. A priority is higher as the generation of LTOtechnology is newer. In the case where there are tape drives with thesame generation, a higher priority is given as a slot number used as abackup destination is smaller.

In addition, the tape state monitoring unit 271 retrieves information ona backup job from the volume-based knowledge table 83, and stores theinformation in the job management table 85. For example, when a backupjob is completed and a media unmounting notification for a tape drive onwhich data has been written in the backup job arrives, the tape statemonitoring unit 271 retrieves information on the backup job.

FIG. 34 is a flowchart of how to retrieve information on a backup job.This backup job retrieval process of FIG. 34 will be describedstep-by-step.

At operation S81, the tape state monitoring unit 271 selects knowledgetime frames for state merging from the volume-based knowledge table 83.For example, to merge states on a knowledge time frame basis, the tapestate monitoring unit 271 selects the same knowledge time frame of eachday for the state merging. Then, the tape state monitoring unit 271creates a merged knowledge table by merging information for the selectedknowledge time frames.

At operation S82, the tape state monitoring unit 271 takes successiveknowledge time frames with a “busy” state in the merged knowledge tablecreated at operation S81 as time frames for one backup job.

At operation S83, the tape state monitoring unit 271 assigns the backupjob determined at operation S82 a job number that is unique in theknowledge period.

At operation S84, the tape state monitoring unit 271 stores theinformation on the backup job determined at operation S82, in the jobmanagement table 85. Then, the tape state monitoring unit 271 sorts thebackup jobs in the job management table 85 in order of priority.

At operation S85, the tape state monitoring unit 271 sets a job numberin the Job State field of the merged knowledge table, in place of thesuccessive “busy” state.

The following describes an example of how to retrieve a backup job fromthe volume-based knowledge table 83 illustrated in FIG. 32.

FIG. 35 illustrates an example merged knowledge table in which data ismerged on a knowledge time frame basis. The merged knowledge table 83 ahas almost the same data structure as the volume-based knowledge table83, excepting that the merged knowledge table 83 a has fields forAverage Write Count and Average Backup Time, instead of the Write Countfield and Backup Time field of the volume-based knowledge table 83,respectively.

The Job State field of the merged knowledge table 83 a indicates a“busy” state if at least one of merged records (records corresponding tothe same knowledge time frame of each day) has a job state of “busy”.The Average Write Count field indicates an average number of writescalculated from the merged records. The Average Backup Time fieldindicates an average backup time calculated from the merged records. TheSlot field indicates a slot number set in the merged records.

From such the merged knowledge table 83 a, successive records with a“busy” state are retrieved.

FIG. 36 illustrates an example of retrieving records with “busy” state.Referring to the example of FIG. 36, the merged knowledge table 83 a hasknowledge time frames of “04-05”, “05-06”, and “06-“07” with a job stateof “busy”. The other knowledge time frames have a job state of “idle”.Therefore, the records of the knowledge time frames of “04-05”, “05-06”,and “06-07” are retrieved from the merged knowledge table 83 a.

The tape state monitoring unit 271 recognizes records of successiveknowledge time frames out of the retrieved records, as records for onebackup job. Then, the tape state monitoring unit 271 creates andregisters backup job information based on the retrieved records in thejob management table 85.

FIG. 37 illustrates an example of creating a job management table.Backup job information 83 b has fields for Job No., Average Write Count,Average Backup Time, Average Throughput (write count per second), SourceCopy Volume, and Slot (medium).

The Job No. field indicates a job number uniquely identifying a backupjob in a knowledge period. The Average Write Count field indicates atotal value of the average write counts of the records belonging to acorresponding backup job of the merged knowledge table 83 a. The AverageBackup Time field indicates a total value of the average backup times ofthe records belonging to a corresponding backup job of the mergedknowledge table 83 a. The Average Throughput field indicates a valueobtained by dividing an average write count by an average backup time,as an average throughput. The Source Copy Volume field indicates the LUNof a backup source copy volume for a corresponding backup job. The Slotfield indicates the slot number of a slot having inserted therein abackup destination medium for a corresponding backup job. That is, aslot number set in the records belonging to the backup job of the mergedknowledge table 83 a is set in this Slot field.

The created backup job information 83 b is registered in the jobmanagement table 85. The job management table 85 has fields forPriority, Job No., Average Write Count, Average Backup Time, AverageThroughput, Source Copy Volume, and Slot. The fields other than thePriority field have the same data as the corresponding fields of thebackup job information 83 b.

The Priority field indicates a priority of a backup job. The Priorityfield has no entry immediately after the backup job information 83 b isregistered.

When the backup job information relating to all backup jobs detected ina knowledge period is registered in the job management table 85, thetape state monitoring unit 271 determines the priority of each backupjob. Then, the tape state monitoring unit 271 sorts the backup jobinformation in order of priority. At this time, the tape statemonitoring unit 271 gives a higher priority to a job with a lowerthroughput. In the case where there are jobs with the same throughput,the tape state monitoring unit 271 gives a higher priority to a job witha smaller data size (average write count). Then, the tape statemonitoring unit 271 gives sequentially increasing numbers to the backupjob information sorted in order of priority in the job management table85, i.e., gives the smallest number to backup job information with thehighest priority.

After that, job numbers are set in the Job State field in the mergedknowledge table 83 a.

FIG. 38 illustrates an example merged knowledge table in which jobnumbers are set. Referring to the example of FIG. 38, a job number of“1” is set in the Job State field corresponding to the knowledge timeframes of “04-05”, “05-06”, and “06-07” of the merged knowledge table 83a, instead of “busy”.

Then, the tape state monitoring unit 271 organizes data (knowledge data)set in the merged knowledge table 83 a in which job numbers are set, ona knowledge time frame basis or on a day basis. The knowledge data isorganized when a knowledge period elapses, for example. The process oforganizing knowledge data is performed in the same way as the process oforganizing the knowledge data of a business volume illustrated in FIG.17.

For example, the tape state monitoring unit 271 organizes knowledge dataon a knowledge time frame basis or on a day basis. At this time, thetape state monitoring unit 271 is able to organize knowledge data foreach backup source copy volume or tape drive.

FIG. 39 illustrates an example data structure of an organized knowledgetable in which knowledge data is organized on a knowledge time framebasis for each copy volume. The organized knowledge table 91 has fieldsfor Knowledge Period, Knowledge Time Frame, and State for each copyvolume.

The Knowledge Period field indicates a knowledge period. The KnowledgeTime Frame field indicates a knowledge time frame. The State field foreach copy volume indicates the state of the copy volume or the jobnumber of a backup job, for a corresponding knowledge time frame.

FIG. 40 illustrates an example data structure of an organized knowledgetable in which knowledge data is organized on a knowledge time framebasis for each tape drive. The organized knowledge table 92 is createdfor each tape drive by organizing data of the drive-based knowledgetable 84. The organized knowledge table 92 has fields for KnowledgePeriod, Knowledge Time Frame, and State for each Tape Drive.

The Knowledge Period field indicates a knowledge period. The KnowledgeTime Frame field indicates a knowledge time frame. The State field foreach tape drive indicates the state of the tape drive for acorresponding knowledge time frame. In this connection, priority is setto each tape drive.

FIG. 41 illustrates an example data structure of an organized knowledgetable in which knowledge data is organized on a day basis for each copyvolume. The organized knowledge table 93 has fields for Day, and Statefor each copy volume.

The Day field indicates a day of a knowledge period. The State field foreach copy volume indicates the state of the copy volume or the jobnumber of a backup job, for a corresponding day.

FIG. 42 illustrates an example data structure of organized knowledgetable in which knowledge data is organized on a day basis for each tapedrive. The organized knowledge table 94 is created for each tape driveby organizing data of the drive-based knowledge table 84. The organizedknowledge table 94 has fields for Day, and State for each tape drive.

The Day field indicates a day of a knowledge period. The State field foreach tape drive indicates the state of the tape drive for acorresponding day. In this connection, priority is set to each tapedrive.

The following describes a matrix for determining a collection procedureat operation S62 of FIG. 28, with reference to FIGS. 43 and 44. Togetherwith determining a collection procedure by using a matrix, data in thedata collection table 81 illustrated in FIG. 29 is appropriatelyupdated, and a response to a notification input to the tape device 200is intentionally delayed. The data in a record corresponding to thecurrent data collection time frame is updated in the data collectiontable 81. In addition, a collection procedure is determined for eachtape drive.

FIG. 43 is a first diagram illustrating an example matrix. The matrix330 has Operation State for backup destination tape drives as the labelof lines, and also has Notification Details as the label of rows. Out ofa variety of notification details, media mounting, media allocation,write, and media unmounting are notifications for the tape device 200.

The operation states for tape drives are roughly divided into a backupjob in progress and a D2D backup in progress. A period from mediamounting until media unmounting in a backup by the backup server 30 istaken as a period for a backup job in progress. A period during which aD2D backup is performed in the disk device 100 is taken as a period fora D2D backup in progress. More specifically, this period is a periodafter the tape device 200 receives a D2D session establishmentnotification from the disk device 100 until the tape device 200 receivesa session disconnection notification. FIG. 43 illustrates proceduresaccording to states of a backup job in progress and notificationdetails.

During a backup job in progress, there are states “idle”, “mount”,“ready”, and “backup”. The “idle” state is a state where a tape drive isnot used. The “mount” state is a state where a tape drive is mounted.The “ready” state is a state where the tape drive is ready to receive arequest for read or write on a medium. The “backup” state is a statewhere writing of backup data is being performed by the tape drive.

The notification details include media mounting, media allocation,write, media unmounting, D2D backup session establishment, and D2Dbackup session disconnection.

The matrix 330 defines data collection procedures according to the stateof a tape drive of the time when the tape drive receives a notificationfrom the disk device 100 or backup server 300 and the details of thenotification. In this connection, each notification includes the driveID of a specified tape drive, and a collection procedure is determinedon the basis of the state of the tape drive identified by the drive IDand the details of the notification.

The following collection procedures are adopted when a backup is inprogress.

[The Case of Tape Drive in “Idle” State]

When a media mounting notification arrives while a tape drive has the“idle” state, the tape state monitoring unit 271 executes “procedure#1”. In the “procedure #1”, the tape state monitoring unit 271 performsa candidate search process for searching for candidate backup sourcecopy volumes. As conditions for the candidate search, a copy volume with“read=0” (read count is 0) is set. Then, the tape state monitoring unit271 executes a process of inserting a medium into the slot of the tapedrive, and changes the state to “mount” in the data collection table 81.

When a D2D backup session establishment notification arrives while thetape drive has the “idle” state, the tape state monitoring unit 271changes the state to “mount delay” in the data collection table 81.Then, the tape state monitoring unit 271 stores the LUN of a copy volumeindicated in the session establishment notification, in the datacollection table 81.

[The Case of Tape Drive in “Mount” State]

When a media allocation notification arrives while the tape drive hasthe “mount” state, the tape state monitoring unit 271 executes“procedure #2”. In the “procedure #2”, the tape state monitoring unit271 performs a candidate filtering search process to narrow downcandidate backup source copy volumes. At this time, as conditions forthe candidate search, a copy volume with “read=0” (read count is 0) isset. Then, the tape state monitoring unit 271 changes the state to“ready” in the data collection table 81.

When a media unmounting notification arrives while the tape drive hasthe “mount” state, the tape state monitoring unit 271 changes the stateto “idle” in the data collection table 81.

When a D2D backup session establishment notification arrives while thetape drive has the “mount” state, the tape state monitoring unit 271changes the state to “ready delay” in the data collection table 81.Then, the tape state monitoring unit 271 stores the LUN of a copy volumeindicated in the session establishment notification, in the datacollection table 81.

[The Case of Tape Drive in “Ready” State]

When a write notification arrives while the tape drive has the “ready”state, the tape state monitoring unit 271 executes “procedure #3”. Inthe “procedure #3”, the tape state monitoring unit 271 performs acandidate filtering search process. At this time, as conditions for thecandidate search, a copy volume with “read!=0” (read count is not “0”)is set. Then, the tape state monitoring unit 271 increments the writecount of the current record for the data collection by one in the datacollection table 81. In this case, the tape state monitoring unit 271keeps the “ready” state in the data collection table 81.

When a media unmounting notification arrives while the tape drive hasthe “ready” state, the tape state monitoring unit 271 changes the stateto “idle” in the data collection table 81.

When a D2D backup session establishment notification arrives while thetape drive has the “ready” state, the tape state monitoring unit 271changes the state to “write delay” in the data collection table 81.Then, the tape state monitoring unit 271 stores the LUN of a copy volumeindicated in the session establishment notification, in the datacollection table 81.

[The Case of Tape Drive in “Backup” State]

When a write notification arrives while the tape drive has the “backup”state, the tape state monitoring unit 271 executes “procedure #4”. Inthe “procedure #4”, the tape state monitoring unit 271 increments thewrite count of the current record for the data collection by one in thedata collection table 81. In this case, the tape state monitoring unit271 keeps the “backup” state in the data collection table 81.

When a media unmounting notification arrives while the tape drive hasthe “backup” state, the tape state monitoring unit 271 executes“procedure #5”. In the “procedure #5”, the tape state monitoring unit271 performs a candidate filtering search process. As conditions for thecandidate search, a copy volume with “read=0” (read count is “0”) isset. If the tape state monitoring unit 271 finds a copy volume for thebackup through the candidate filtering search process, the tape statemonitoring unit 271 aggregates the backup job information on this backupjob, and stores the resultant in the job management table 85. Then, thetape state monitoring unit 271 changes the state to “idle” in the datacollection table 81.

When a D2D backup session establishment notification arrives while thetape drive has the “backup” state, the tape state monitoring unit 271changes the state to “backup delay” in the data collection table 81.Then, the tape state monitoring unit 271 stores the LUN of a copy volumeindicated in the session establishment notification, in the datacollection table 81.

FIG. 44 is a second view illustrating the example matrix. During a D2Dbackup in progress, there are states including “mount delay”, “readydelay”, “write delay”, and “backup delay”. The “mount delay” is a statewhere a D2D backup is being performed in the disk device 100 and a tapedrive is not used. The “ready delay” is a state where a D2D backup hasstarted in the disk drive 100 after a tape drive was mounted, and amedia allocation notification has not arrived. The “write delay” is astate where a D2D backup has started in the disk device 100 after thestate was changed to “ready”, and a write notification has not arrivedin a backup job. The “backup delay” is a state where a D2D backup hasstarted in the disk device 100 after a write notification arrived in abackup job, and a next write notification has not arrived.

[The Case of Tape Drive in “Mount Delay” State]

When a media mounting notification arrives while the tape drive has the“mount delay” state, the tape state monitoring unit 271 executes“procedure #6”. In the “procedure #6”, the tape state monitoring unit271 performs a candidate search process. As conditions for the candidatesearch, a copy volume with “read=0” (read count is “0”) is set. Then,the tape state monitoring unit 271 performs a process of inserting amedium into the slot of the tape drive. Then, the tape state monitoringunit 271 performs a delay target determination process to determinewhether or not a backup source copy volume of the backup job sending thenotification needs a delay in the tape drive. If the copy volume needsthe delay, the tape state monitoring unit 271 changes the state to“ready delay” and performs a mounting delay process. The mounting delayprocess is a process in which a response indicating completion ofmounting is sent a predetermined delay time after the mounting of thetape drive is completed. If the tape drive does not need the delay, onthe contrary, the tape state monitoring unit 271 changes the state to“mount”. Then, the tape state monitoring unit 271 deletes the LUN of thecopy volume from the data collection table 81.

When a D2D backup session disconnection notification arrives while thetape drive has the “mount delay” state, the tape state monitoring unit271 changes the state to “idle”, and then deletes the LUN of the copyvolume from the data collection table 81.

[The Case of Tape Drive in “Ready Delay” State]

When a media allocation notification arrives while the tape drive hasthe “ready delay” state, the tape state monitoring unit 271 executes“procedure #7”. In the “procedure #7”, the tape state monitoring unit271 performs a candidate filtering search process. As conditions for thecandidate search, a copy volume with “read=0” (read count is “0”) isset. Then, the tape state monitoring unit 271 performs a delay targetdetermination process. If a backup source copy volume needs a delay, thetape state monitoring unit 271 changes the state to “write delay”, andperforms a ready delay process. The ready delay process is a process inwhich a ready response is sent a predetermined delay time afterallocation of the tape drive is completed. If the backup source copyvolume does not need the delay, the tape state monitoring unit 271changes the state to “ready”. Then, the tape state monitoring unit 271deletes the LUN of the copy volume from the data collection table 81.

When a media unmounting notification arrives while the tape drive hasthe “ready delay” state, the tape state monitoring unit 271 changes thestate to “idle”, and then deletes the LUN of the copy volume from thedata collection table 81.

When a D2D backup session disconnection notification arrives while thetape drive has the “ready delay” state, the tape state monitoring unit271 changes the state to “mount”, and then deletes the LUN of the copyvolume from the data collection table 81.

[The Case of Tape Drive in “Write Delay” State]

When a write notification arrives while the tape drive has the “writedelay” state, the tape state monitoring unit 271 executes “procedure#8”. In the “procedure #8”, the tape state monitoring unit 271 performsa candidate filtering search process. As conditions for the candidatesearch, a copy volume with “read!=0” (read count is not “0”) is set.Then, the tape state monitoring unit 271 increments the write count ofthe current record for the data collection by one. Then, the tape statemonitoring unit 271 performs a delay target determination process. Ifthe backup source copy volume needs a delay, the tape state monitoringunit 271 changes the state to “backup delay” and performs a write delayprocess. This write delay process is a process in which a writecompletion response is sent a predetermined delay time after data iswritten on a medium by the tape drive. If the backup source copy volumedoes not need the delay, the tape state monitoring unit 271 changes thestate to “backup”. Then, the tape state monitoring unit 271 deletes theLUN of the copy volume from the data collection table 81.

When a media unmounting notification arrives while the tape drive hasthe “write delay” state, the tape state monitoring unit 271 changes thestate to “idle”, and then deletes the LUN of the copy volume from thedata collection table 81.

When a D2D backup session disconnection notification arrives while thetape drive has the “write delay” state, the tape state monitoring unit271 changes the state to “ready”, and then deletes the LUN of the copyvolume from the data collection table 81.

[The Case of Tape Drive in “Backup Delay” State]

When a write notification arrives while the tape drive has the “backupdelay” state, the tape state monitoring unit 271 executes “procedure#9”. In the “procedure #9”, the tape state monitoring unit 271increments the write count of the current record for the data collectionby one, and performs a delay target determination process. If a backupsource copy volume needs a delay, the tape state monitoring unit 271keeps the “backup delay” state and performs a write delay process. Ifthe backup source copy volume does not need the delay, the tape statemonitoring unit 271 changes the state to “backup”, and deletes the LUNof the copy volume from the data collection table 81.

When a media unmounting notification arrives while the tape drive hasthe “backup delay” state, the tape state monitoring unit 271 executes“procedure #10”. In the “procedure #10”, the tape state monitoring unit271 executes a candidate filtering search process. As conditions for thecandidate search, a copy volume with “read=0” (read count is “0”) isset. If the tape state monitoring unit 271 finds a backup source copyvolume through the candidate filtering search, the tape state monitoringunit 271 aggregates and stores the backup job information on this backupin the job management table 85. Then, the tape state monitoring unit 271changes the state to “idle” in the data collection table 81, and deletesthe LUN of the copy volume from the data collection table 81.

When a D2D backup session disconnection notification arrives while thetape drive has the “backup delay” state, the tape state monitoring unit271 changes the state to “backup”, and then deletes the LUN of the copyvolume from the data collection table 81.

As described above, when a notification is input from the disk device100 or backup server 30, an appropriate procedure for the state of atape drive is taken in the tape drive according to the definitions ofthe matrix 330. In this connection, each of the media mounting, mediaallocation, write, and media unmounting notifications specifies a tapedrive, and a procedure is executed only on the specified tape driveaccording to the matrix 330. On the other hand, each of the D2D backupsession establishment and D2D backup session disconnection notificationsdoes not specify a tape drive, and a procedure is executed on all tapedrives according to the matrix 330.

The following describes the candidate search process to be performed inthe “procedure #1” and procedure #6” in detail.

FIG. 45 is a flowchart of a candidate search process. This process ofFIG. 45 will be described step-by-step.

At operation S91, the tape state monitoring unit 271 consults the datacollection table 61 regarding copy volumes (refer to FIG. 22) to checkinformation on the copy volumes for the same time frame as a currentdata collection time frame in question in the data collection table 81.

At operation S92, the tape state monitoring unit 271 selects one copyvolume.

At operation S93, the tape state monitoring unit 271 determines whetherthe read count of the selected copy volume satisfies the conditions forthe candidate search. For example, the conditions for the candidatesearch in the “procedure #1” and “procedure #6” illustrated in FIG. 43are that a read count is “0”. If the conditions are satisfied, the tapestate monitoring unit 271 proceeds to operation S94; otherwise, the tapestate monitoring unit 271 proceeds to operation S95.

At operation S94, the tape state monitoring unit 271 takes the selectedcopy volume as a candidate copy volume. More specifically, the tapestate monitoring unit 271 registers the identification number of theselected copy volume in the Candidate Copy Volume field corresponding tothe current data collection time frame in question in the datacollection table 81 (refer to FIG. 29) of the tape device 200.

At operation S95, the tape state monitoring unit 271 determines whetherthere is any unselected copy volume or not. If this determination isaffirmative, the tape state monitoring unit 271 proceeds back tooperation S92; otherwise, the tape state monitoring unit 271 completesthe candidate search process.

As described above, a candidate copy volume for a backup job is foundfrom among a plurality of copy volumes on the basis of the read countsof the copy volumes. For example, the “procedure #1” and “procedure #6”of FIG. 43 are executed when a media mounting notification arrives. Themedia mounting is performed when a backup starts in a backup job. Thismeans that a sequential read has not been performed in the backup sourcecopy volume. Therefore, a copy volume in which a sequential read is notperformed (read count is “0”) when the media mounting notificationarrives is detected as a candidate backup source copy volume.

The following describes the candidate filtering search process to beexecuted in the “procedure #2”, “procedure #3”, “procedure #5”,“procedure #7”, “procedure #8”, and the “procedure #10” in detail.

FIG. 46 is a flowchart of a candidate filtering search process. Thisprocess of FIG. 46 will be described step-by-step.

At operation S101, the tape state monitoring unit 271 consults the datacollection table 61 (refer to FIG. 22) to check information for the sametime frame as a current data collection time frame in question in thedata collection table 81. At this time, the tape state monitoring unit271 checks the information only on copy volumes that are candidates inthe previous data collection time frame, which is one before the currentdata collection time frame.

At operation S102, the tape state monitoring unit 271 selects one copyvolume that is a candidate copy volume in the previous data collectiontime frame.

At operation S103, the tape state monitoring unit 271 determines whetherthe read count of the selected copy volume satisfies the conditions forthe candidate search or not. For example, the conditions for thecandidate search in the “procedure #2” and “procedure #5” of FIG. 43 and“procedure 7” of FIG. 44 are that the read count is “0”. On the otherhand, the conditions for the candidate search in the “procedure #3” and“procedure #8” are that the read count is not “0”. If the conditions aresatisfied, the tape state monitoring unit 271 proceeds to operationS104; otherwise, the tape state monitoring unit 271 proceeds tooperation S105.

At operation S104, the tape state monitoring unit 271 takes the selectedcopy volume as a candidate copy volume. More specifically, the tapestate monitoring unit 271 registers the identification number of theselected copy volume in the Candidate Copy Volume field for the datacollection time frame in question in the data collection table 81 (referto FIG. 29) of the tape device 200.

At operation S105, the tape state monitoring unit 271 determines whetherthere is any unselected copy volume out of the copy volumes which arecandidates in the previous data collection time frame. If thisdetermination is affirmative, the tape state monitoring unit 271proceeds back to operation S102; otherwise, the tape state monitoringunit 271 completes the candidate search process.

As described above, the backup source copy volumes are narrowed down onthe basis of the read counts of the copy volumes. For example, the“procedure #2” or “procedure #5” of FIG. 43 or the “procedure #7” ofFIG. 44 is executed when a media allocation or media unmountingnotification arrives. The media allocation is performed when a data copyprocess starts in a backup job. In addition, the media unmounting isperformed when the data copy process is completed in the backup job.This means that a sequential read is not performed in the backup sourcecopy volume during either the media allocation or media unmounting.Therefore, a copy volume in which a sequential read is not performed(read count is “0”) when a media allocation or media unmountingnotification arrives is taken as a backup candidate.

On the other hand, the “procedure #3” of FIG. 43 and “procedure #8” ofFIG. 44 are executed when a write notification arrives. A writenotification for write to the tape device 200 is output after asequential read starts in the backup source copy volume in a backup.This means that a sequential read is performed in the backup source copyvolume in the time frame in which the write notification is output.Therefore, a copy volume in which a sequential read is performed (readcount is other than “0”) when the write notification arrives is taken asa backup candidate.

The following describes a delay target determination process to beperformed in the “procedure #6”, “procedure #7”, “procedure #8”, and“procedure #9” of FIG. 44 in detail.

FIG. 47 is a flowchart of a delay target determination process. Thisprocess of FIG. 47 will be described step-by-step.

At operation S111, the tape state monitoring unit 271 consults the datacollection table 81 to check the record of a tape drive in questioncorresponding to the current data collection time frame, and comparecandidate copy volumes with a D2D backup destination copy volume.

At operation S112, the tape state monitoring unit 271 determines whetherthe D2D backup destination copy volume is included in the candidate copyvolumes. If this determination is affirmative, this means that a backupjob may be being executed using the backup destination copy volume ofthe D2D backup. The tape state monitoring unit 271 proceeds to operationS113 if the D2D backup destination copy volume is included in thecandidate copy volumes. The tape state monitoring unit 271 proceeds tooperation S116 otherwise.

At operation S113, the tape state monitoring unit 271 determines whetheror not the tape drive in question has one of the “mount delay” and“ready delay” states. The tape state monitoring unit 271 proceeds tooperation S114 if the tape drive has the “mount delay” or “ready delay”state. The tape state monitoring unit 271 proceeds to operation S115otherwise.

At operation S114, the tape state monitoring unit 271 determines whetherthere is only one candidate copy volume. If this determination isaffirmative, the tape state monitoring unit 271 proceeds to operationS115; otherwise, the tape state monitoring unit 271 proceeds tooperation S116.

At operation S115, the tape state monitoring unit 271 sets the tapedrive in question as a delay target. Then, the delay targetdetermination process is completed.

At operation S116, the tape state monitoring unit 271 completes thisdelay target determination process without setting the tape drive inquestion as a delay target.

As described above, if there is a possibility that a backup job usingthe backup destination copy volume of a D2D backup is executed, the tapedrive in which data is to be stored in the backup job is taken as adelay target.

In this connection, when the tape drive has a “mount delay” or “readydelay” state, the tape drive is taken as a delay target if the candidatecopy volume is the only candidate copy volume detected. This is becausea data read is not performed in the copy volume when media mounting ormedia allocation is executed in the tape drive in the “mount delay” or“ready delay” state. If a data read is not executed in the copy volume,there is no interference in access to the business volume under the D2Dbackup.

However, issuance of the media mounting or media allocation notificationimplies that a write notification will be issued in the backup job. Inthe second embodiment, in the case where a tape drive has the “mountdelay” or “ready delay” state, the tape drive is taken as a delay targetonly if candidate copy volumes are narrowed down to one, meaning that abackup source copy volume is found. Therefore, when a D2D backup in thedisk device 100 and a backup job under the control of the backup server30 are executed on the same copy volume, the start of the copy in thebackup job is delayed. As a result, a period during which a data writeon a copy volume in the D2D backup and a data read from the copy volumein the backup job are performed at the same time is prevented.

In addition, in the case where the tape drive has a “mount delay” or“ready delay” state, a delay process is not performed if candidate copyvolumes are not narrowed down to one. This avoids performing a delayprocess that is not needed. That is, a delay process is skipped whenthere is a low possibility of an adverse effect to data inputs andoutputs to a business volume. As a result, a decrease in the backup jobefficiency may be suppressed.

In addition, when a drive has a state other than the “mount delay” and“ready delay” states (i.e., “write delay” or “backup delay”), the driveis taken as a delay target even if there is a plurality of candidatecopy volumes. This is because, if a write notification is issued, asequential data read from a copy volume is executed, and there may beinterference in a business volume under the D2D backup using the copyvolume as a backup destination. That is, to make sure to suppress theinterference in the business volume, a write delay process is performedin the data write to the tape drive even if there is a plurality ofcandidate copy volumes. When the write delay process is performed, aninterval for a sequential data read from the copy volume is prolonged.As a result, a processing efficiency of data write to the copy volume ina D2D backup is improved, and a decrease in processing efficiency ofaccesses from the business server 20 to the business volume issuppressed.

By the way, a delay process may always be performed when a mediamounting, media allocation, or write notification is issued in a backupjob while the D2D backup is performed, without performing thedetermination process of FIG. 47.

[Improvement Proposal for Backup Schedule]

The following describes a process for proposing an improved backupschedule that realizes an efficient and safety operation. This backupschedule improvement proposing process first classifies backups. Thebackup classification is a process of analyzing an access frequency onthe basis of an organized knowledge table, and determines backup days.

FIG. 48 illustrates a procedure of a backup classification process. Thisprocess of FIG. 48 will be described step-by-step.

At operation S121, the tape state monitoring unit 271 consults theorganized knowledge table 72 for business volumes in which data isorganized on a day basis, to select one day.

At operation S122, the tape state monitoring unit 271 determines whethera business volume of the selected day has an “idle” state or not. Ifthis determination is affirmative, the tape state monitoring unit 271proceeds to operation S123; otherwise, the tape state monitoring unit271 proceeds to operation S124.

At operation S123, the tape state monitoring unit 271 determines that abackup job on the day following the selected day is not needed. Then,the process proceeds to operation S125.

At operation S124, the tape state monitoring unit 271 determines that abackup job on the day following the selected day is needed.

At operation S125, the tape state monitoring unit 271 determines whetherthere is any unselected day. If this determination is affirmative, thetape state monitoring unit 271 proceeds back to operation S121;otherwise, the tape state monitoring unit 271 proceeds to operationS126.

At operation S126, the tape state monitoring unit 271 notifies theadministrator of the result of determining the necessity of backups foreach day via an email or the like.

FIG. 49 illustrates an example classification of backups. Referring toFIG. 49, only information on “LUN2” is retrieved from the organizedknowledge table 72 for business volumes. In addition, it is assumed thatthe data of the business volume of “LUN2” is backed up to the copyvolume of “LUN2”. In FIG. 49, information on the copy volume of “LUN2”is retrieved from the organized knowledge table 93 of the tape device200.

The business volume of “LUN2” has a “busy” state only for Wednesday andan “idle” state for the other days. This means that the business volumeof “LUN2” is used only on Wednesday. On the other hand, a backup job “3”is executed every day from Monday to Friday. If the business volume isused only on Wednesday, a backup job may be executed on a day followingWednesday, for example, on Thursday. A backup job is considered not tobe needed on days other than Thursday.

In such a case, the tape state monitoring unit 271 notifies theadministrator, via an email or the like, that only Thursday issufficient for executing a backup job of the copy volume of “LUN2”. As aresult, the administrator is able to create an efficient backup jobschedule.

In addition, the tape state monitoring unit 271 is capable of proposinga reschedule according to priority with taking an overlap of jobs intoconsideration.

FIG. 50 is a flowchart of a reschedule proposing process. This processof FIG. 50 will be described step-by-step.

At operation S131, the tape state monitoring unit 271 consults theorganized knowledge table 91 where data is organized for each copyvolume in the tape device 200 to check the execution state of a backupjob for each copy volume.

At operation S132, the tape state monitoring unit 271 determines whetherthere are backup jobs which overlap in execution time. If there are suchbackup jobs, the tape state monitoring unit 271 proceeds to operationS133; otherwise, the tape state monitoring unit 271 completes thisprocess.

At operation S133, the tape state monitoring unit 271 selects a backupjob with the highest priority among the overlapping backup jobs, as ajob to be rescheduled. The priority of each backup job is determined onthe basis of the job management table 85 (refer to FIG. 37).

At operation S134, the tape state monitoring unit 271 checks a timeavailable for rescheduling. For example, the tape state monitoring unit271 checks the execution times of backup jobs (other backup jobs) otherthan the backup job to be rescheduled. The tape state monitoring unit271 also checks an available time (time of “idle”) from the state of thebackup source copy volume of the backup job to be rescheduled. Then, thetape state monitoring unit 271 determines the available time of thebackup source copy volume of the backup job to be rescheduled, otherthan the execution times of the other backup jobs, as a time to be usedfor the rescheduling.

At operation S135, the tape state monitoring unit 271 reschedules thebackup job to be rescheduled for the available time detected atoperation S134, to thereby create a proposed schedule table 310.

At operation S136, the tape state monitoring unit 271 determines whetherthere are other backup jobs which overlap in execution time. If thereare such other backup jobs, the tape state monitoring unit 271 proceedsback to operation S133; otherwise, the tape state monitoring unit 271proceeds to operation S137.

At operation S137, the tape state monitoring unit 271 executes a usedrive search process, which will be described later (with reference toFIG. 55).

At operation S138, the tape state monitoring unit 271 notifies theadministrator of the details of the proposed schedule table via an emailor the like.

The above-described technique makes it possible to propose a schedule inwhich time frames for backup jobs do not overlap. The followingdescribes a specific example of the reschedule proposing process.

FIG. 51 illustrates an example organized knowledge table in whichknowledge data is organized on a knowledge time frame basis for eachcopy volume. It is assumed that, in the organized knowledge table 91 ofFIG. 51, all time frames except for the knowledge time frames with thejob number of a backup job are available (“idle” state).

The organized knowledge table 91 of FIG. 51 indicates that three backupjobs are executed in a time frame from 05:00 to 07:00, and that twobackup jobs are executed in a time frame from 07:00 to 08:00.

Assume now that a backup job with a job number of “3” has the highestpriority, a backup job with a job number of “2” has the second highestpriority, and a backup job with a job number of “1” has the lowestpriority. In this case, the backup job with the job number of “3” isselected as a backup job to be rescheduled.

Then, an available time for a backup is found.

FIG. 52 illustrates an example of searching for an available time.Referring to FIG. 52, the execution states of the other backup jobs arejudged on the basis of the organized knowledge table 91 for each copyvolume. In addition, the execution state of a D2D backup to a copyvolume of “LUN2” which is a backup source of a backup to be rescheduledis judged based on the organized knowledge table 71.

The example of FIG. 52 indicates a result of searching for an availabletime in knowledge time frames on the right side. “Busy” is set in timeframes in which the other backup jobs are executed. In addition, “busy”is set in time frames in which a D2D backup to the copy volume of “LUN2”is executed. The other time frames are considered available (“idle”state). Then, the backup job with the job number of “3” is rescheduledfor an available time, thereby generating a proposed schedule table 310.

FIG. 53 illustrates an example proposed schedule table. The proposedschedule table 310 has fields for Knowledge Time Frame, and State foreach copy volume. The Knowledge Time Frame field indicates a knowledgetime frame obtained by dividing one day by a knowledge unit. The Statefield for each copy volume indicates the job number of a backup jobexecuted in a corresponding time frame.

Referring to FIG. 53, the backup job with a job number of “3” does notoverlap with the other backup jobs by rescheduling the backup job withthe job number of “3” for a time frame from 16:00 to 20:00. However, theexample of FIG. 53 indicates that the backup jobs with job numbers of“1” and “2” still overlap in execution time. Therefore, the backup jobwith job number of “2” with higher priority is rescheduled.

FIG. 54 illustrates an example rescheduling of a backup job with jobnumber of “2”. To reschedule the second backup job, the proposedschedule table 310 is used for checking the execution states of theother backup jobs. That is, the execution times of the other backup jobsare judged on the condition that the backup job previously rescheduledis fixed in the rescheduled time frames. That is, on the basis of theproposed schedule table 310 and organized knowledge table 71, theavailable time of the backup source copy volume of “LUN2” for the backupjob to be rescheduled is determined. Then, the backup job to berescheduled is rescheduled for an available time frame, thereby updatingthe proposed schedule table 310.

The following describes a use drive search process.

FIG. 55 is a flowchart of a use drive search process. This process ofFIG. 55 will be described step-by-step.

At operation S141, the tape state monitoring unit 271 checks theschedule of each backup job on the basis of the proposed schedule table310.

At operation S142, the tape state monitoring unit 271 selects a tapedrive in order of priority, highest first, for searching for anavailable time. A higher priority is given to a tape drive which isbased on a newer generation of LTO technology.

At operation S143, the tape state monitoring unit 271 determines whetherthe selected tape drive is free (the “idle” state) in the time frame forwhich a backup job is scheduled. The available time frame of a tapedrive is determined on the basis of the organized knowledge table 92 inwhich data is organized on a knowledge time frame basis for each tapedrive. The tape state monitoring unit 271 proceeds to operation S144 ifthis determination is affirmative. The tape state monitoring unit 271proceeds back to operation S142 otherwise.

At operation S144, the tape state monitoring unit 271 assigns theselected tape drive as a backup destination for the backup job. Then,the use drive selection process is completed.

FIG. 56 illustrates an example allocation of a use drive. Referring tothe example of FIG. 56, the backup jobs with job numbers of “2” and “3”are rescheduled. In addition, the tape drive of “G4_(—)02” has thehighest priority. Therefore, it is determined whether a time frame from10:00 to 12:00 during which a backup job with job number of “2” isexecuted is available, based on the use state of the tape drive of“G4_(—)02”. Referring to the example of FIG. 56, this time frame isavailable. Therefore, the tape drive of “G4_(—)02” is assigned as abackup destination for the backup job with job number of “2”. Similarly,it is determined based on the use state of the tape drive of “G4_(—)02”whether a time frame from 16:00 to 20:00 during which a backup job withjob number of “3” is executed is available. Referring to the example ofFIG. 56, this time frame is available. Therefore, the tape drive of“G4_(—)02” is assigned as a backup destination for the backup job withjob number “3”.

As described above, backup jobs are rescheduled, and a proposed scheduleis provided to the administrator. The administrator then displays theproposed schedule on a screen of his/her terminal device to confirm thedetails of the schedule.

FIG. 57 illustrates an example report screen for a proposed schedule.The report screen 320 provides improved plans, frequency, and use drivefor each backup job. If there is no improved plan, then “NO” isdisplayed.

An improved plan is represented by start time and frequency. The starttime indicates a start time of a backup job. The frequency indicateseveryday process or once-a-week process. In the case of once-a-weekprocess, an appropriate day for a backup job is indicated. In addition,an appropriate tape drive as a backup destination for a backup job isindicated as a use drive.

The administrator checks such the report screen 320 to create anappropriate backup schedule.

In addition, the second embodiment intentionally delays a response toeach kind of notification in the tape device 200 when a D2D backupstarts in the disk device 100 while a backup job is executed.

FIG. 58 illustrates an execution state of a response delay. Asillustrated in FIG. 58, when a D2D backup starts while a backup job ofbacking up data from a copy volume to the tape device 200 is executed,the backup job is delayed intentionally. This intentional delay reducesthe processes of the tape device 200 and eliminates interference inbusiness.

That is to say, a D2D backup involves writing to a copy volume. Manycopy volumes provide a slow access speed. If such a copy volume has aRAID 5 structure, a write penalty occurs, and data is written at aslower speed. The write penalty is a process of reading data and paritybefore update and updating the parity at the time of a data update. Thatis, in the RAID 5, data is updated only after the data and parity areread, which needs a longer time for writing.

When a D2D backup is executed while a D2T backup job is executed, datawrite to the copy volume in the D2D backup is further delayed.Therefore, the D2D backup takes a longer time. This produces aninfluence of prolonging a period during which data is not written in abackup source business volume of the D2D backup.

Therefore, the second embodiment intentionally delays a response to eachnotification in the tape device 200. Because of a delay period of abackup job, data write to a copy volume in a D2D backup is smoothlyexecutable.

The following techniques are employed for delaying a response.

(i) A media mounting process is delayed before a backup starts. In thiscase, a response is delayed by a time period (for example, 5 minutes)which does not cause a timeout error.

(ii) A transition time to a “ready” state in response to a mediaallocation notification is delayed after a medium is mounted in a drive.In this case, a ready response is delayed by a time period (for example,10 minutes) which does not cause a timeout error.

(iii) A completion response to a write command (write notification) isdelayed. A backup job to be executed in the backup server 30 issues anext data write command after a response notification to the writecommand arrives. Delaying the completion response to the write commandreduces the number of reads to a disk device.

Such an intentional delay of a response to a tape access in the tapedevice 200 may be executed without the backup server 30 noticing thedelay. That is, efficient backups are realized by controlling the diskdevice 100 and tape device 200. It is very beneficial when theadministrator of the disk device 100 or tape device 200 and theadministrator of the backup server 300 are different.

In this connection, the second embodiment reduces loads on the diskdevice 100, which suppresses troubles due to overloads of the diskdevice 100.

In addition, the second embodiment proposes an appropriate tape drivetogether with an appropriate backup schedule. Using tape drives inaccordance with the proposal optimizes the performance of backups.

Other Embodiments

In the second embodiment, the tape device 200 detects whether a backupis performed, on the basis of whether a sequential read is performed ina copy volume. Alternatively, the disk device 100 may be designed todetect whether a backup from a copy volume is performed or not. In thiscase, the disk device 100 notifies the tape device of the identificationinformation (LUN) of the copy disk in which the backup is performed.

The above processing functions can be realized by using a computer. Inthis case, a program is prepared, which describes the processingcontents of the functions of the information processing apparatus 4, thedisk state monitoring units 151 and 161 of the disk device 100, and thetape state monitoring unit 271 of the tape device 200. The aboveprocessing functions are realized on the computer by executing theprogram. The program describing the needed processes may be recorded ona computer-readable recording medium. Computer-readable recording mediainclude magnetic recording devices, optical discs, magneto-opticalrecording media, semiconductor memories, etc. The magnetic recordingdevices include Hard Disk Drives (HDD), Flexible Disks (FD), media, etc.The optical discs include DVDs, DVD-RAMs, CD-ROM/RWs, etc. Themagneto-optical recording media include Magneto-Optical discs (MO), etc.

To distribute the program, portable recording media, such as DVDs andCD-ROMs, on which the program is recorded may be put on sale.Alternatively, the program may be stored in the storage device of aserver computer and may be transferred from the server computer to othercomputers through a network.

A computer which is to execute the above program stores in its localstorage device the program recorded on a portable recording medium ortransferred from the server computer, for example. Then, the computerreads the program from the local storage device, and runs the program.The computer may run the program directly from the portable recordingmedium. Also, while receiving the program being transferred from theserver computer, the computer may sequentially run this program.

Further, at least part of the above processing functions may be realizedby electronic circuits such as Digital Signal Processor (DSP),Application Specific Integrated Circuit (ASIC), and Programmable LogicDevice (PLD).

The disclosed technique makes it possible to recognize the executionstate of a backup on the basis of internal information of a storagedevice.

All examples and conditional language recited herein are intended forpedagogical purposes to aid the reader in understanding the inventionand the concepts contributed by the inventor to furthering the art, andare to be construed as being without limitation to such specificallyrecited examples and conditions, nor does the organization of suchexamples in the specification relate to a showing of the superiority andinferiority of the invention. Although the embodiments of the presentinvention have been described in detail, it should be understood thatvarious changes, substitutions, and alterations could be made heretowithout departing from the spirit and scope of the invention.

1. An information processing apparatus comprising: an acquisition unit that acquires access information indicating a state of access to a volume of a disk device at least for data read; and a determination unit that detects a volume in which a sequential read was performed, on the basis of the acquired access information, and determines the detected volume as a backup source volume for a backup.
 2. The information processing apparatus according to claim 1, wherein: the acquisition unit acquires an operation instruction made to a tape device regarding the backup of data to a magnetic tape of the tape device; and the determination unit acquires access information at the time of acquisition of the operation instruction made to the tape device, and determines the backup source volume in the disk device for the backup of the data to the magnetic tape specified in the operation instruction.
 3. The information processing apparatus according to claim 2, wherein: the acquisition unit acquires the operation instruction made to the tape device regarding the backup of the data to the magnetic tape of the tape device, and acquires start information and end information indicating start and end of a backup performed between volumes of the disk device; and the information processing apparatus further comprises an instruction unit that causes the tape device to delay responding to the operation instruction in a case where the operation instruction made to the tape device is acquired after acquisition of the start information and before acquisition of the end information.
 4. The information processing apparatus according to claim 3, wherein: the determination unit determines whether a backup destination volume for the backup performed between the volumes of the disk device is the backup source volume in the disk device for the backup of the data to the magnetic tape specified in the operation instruction made to the tape device; and the instruction unit causes the tape device to delay responding to the operation instruction in a case where the determination unit determines that the backup destination volume and the backup source volume are a same volume.
 5. The information processing apparatus according to claim 1, further comprising a scheduling unit that determines a period from start to end of a sequential read as an execution time of a backup, and creates a backup schedule by changing an execution time of at least one of a plurality of backups that overlap in execution time.
 6. The information processing apparatus according to claim 5, wherein the scheduling unit creates the backup schedule by changing the execution time of said one backup to a period during which there is no access to a backup source volume for said one backup.
 7. The information processing apparatus according to claim 5, wherein the scheduling unit preferentially selects a backup with a low throughput from among the plurality of backups that overlap in execution time, and creates the backup schedule by changing the execution time of the selected backup.
 8. The information processing apparatus according to claim 5, wherein the scheduling unit preferentially selects a backup with a small data size from among the plurality of backups that overlap in execution time, and creates the backup schedule by changing the execution time of the selected backup.
 9. The information processing apparatus according to claim 5, wherein: the acquisition unit acquires operation instructions each made to a tape device regarding a backup of data to a magnetic tape of the tape device, the operation instructions each specifying a tape drive; and the scheduling unit determines a use period of each tape drive of the tape device on the basis of the acquired operation instructions, and creates the backup schedule that includes information indicating a tape drive usable in a new execution time to which the execution time of said one backup is changed.
 10. The information processing apparatus according to claim 5, wherein: the acquisition unit acquires access information including a state of data write to each volume of the disk device; the determination unit detects a state of data update in said each volume of the disk device, which is a backup source volume, on a day basis; and the scheduling unit creates the backup schedule in which a backup from said each volume of the disk device is scheduled for a day following a data update day of said each volume.
 11. A tape device comprising: an acquisition unit that acquires access information from a disk device, the access information indicating a state of access to a volume of the disk device at least for data read; and a determination unit that detects a volume in which a sequential read was performed, on the basis of the acquired access information, and determines the detected volume as a backup source volume for a backup.
 12. The tape device according to claim 11, wherein: the acquisition unit monitors inputs of operation instructions to the tape device regarding the backup of data to a magnetic tape of the tape device; and the determination unit acquires access information at the time of an input of an operation instruction to the tape device, and determines the backup source volume in the disk device for the backup of the data to the magnetic tape specified in the operation instruction.
 13. A non-transitory computer-readable recording medium storing a program causing a computer to perform a procedure comprising: acquiring access information indicating a state of access to a volume of a disk device at least for data read; and detecting a volume in which a sequential read was performed, on the basis of the acquired access information, and determining the detected volume as a backup source volume for a backup.
 14. The non-transitory computer-readable recording medium according to claim 13, wherein: said acquiring the access information further acquires an operation instruction made to a tape device regarding the backup of data to a magnetic tape of the tape device; and said determining as the backup source volume includes acquiring access information at the time of an input of the operation instruction to the tape device, and determining the backup source volume in the disk device for the backup of the data to the magnetic tape specified in the operation instruction.
 15. The non-transitory computer-readable recording medium according to claim 13, wherein: said acquiring the access information further acquires the operation instruction made to the tape device regarding the backup of the data to the magnetic tape of the tape device, and start information and end information indicating start and end of a backup performed between volumes of the disk device; and the procedure further comprises causing the tape device to delay responding to the operation instruction in a case where the operation instruction is input to the tape device after acquisition of the start information and before acquisition of the end information.
 16. The non-transitory computer-readable recording medium according to claim 13, wherein the procedure further comprises determining a period from start to end of a sequential read as an execution time of a backup, and creating a backup schedule by changing an execution time of at least one of a plurality of backups that overlap in execution time. 